CN116806246A

CN116806246A - Optical adhesive tape

Info

Publication number: CN116806246A
Application number: CN202280012018.6A
Authority: CN
Inventors: 冲田奈津子; 越智元气; 桥本尚树; 池岛裕美; 野吕弘司
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2021-01-29
Filing date: 2022-01-26
Publication date: 2023-09-26

Abstract

The present invention provides an optical adhesive tape used for a tiled display in which a plurality of image display devices are arranged in a tile shape, wherein gaps between the plurality of image display devices are less likely to be noticeable even in a use environment, transparency is maintained, and a good appearance is maintained. The optical adhesive tape 10A of the present invention has a laminated structure in which a base material 1 and an adhesive layer 2 are laminated, the base material 1 having a first surface 1a and a second surface 1b, and the adhesive layer 2 being laminated on the first surface 1a of the base material 1. When the optical adhesive tape 10A is heated at 60 ℃ in an environment with a relative humidity of 90% for 500 hours, the average dimensional change rate in the width direction and the longitudinal direction is within ±0.15%. The recovery rate of the adhesive layer 2 obtained in the shear test described below was 95% or less. < shear test > the strain A (%) when 500Pa of shear force in 600 seconds torsion direction was applied from above and below the disk-like adhesive layer having a thickness of 2mm and a diameter of 7.9mm and the strain B (%) when 1800 seconds was thereafter held at a shear force of 0Pa were measured at 60 ℃, and the recovery (%) was calculated from the following formula. Recovery (%) = (strain amount a-strain amount B)/strain amount a×100.

Description

Optical adhesive tape

Technical Field

The present invention relates to an optical adhesive tape. More specifically, the present invention relates to an optical adhesive tape suitable for manufacturing a tiled display in which a plurality of image display devices are arranged in a tile shape.

Background

With the increase in image quality of 4K, 8K, and the like, the demand for larger-screen image display devices is growing. In addition, large-screen image display devices are also being used for advertisement display in the open air and public facilities, and signs such as bulletin boards. However, when manufacturing a large-screen image display device, there is a problem in that the yield is reduced and the manufacturing cost is increased. In order to manufacture a large-screen image display device at a lower cost, a tiled display in which a plurality of image display devices are arranged in a tile shape is being studied (for example, patent document 1).

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open publication No. 2017-161634

Disclosure of Invention

Problems to be solved by the invention

In a tiled display, in order to make the gaps between a plurality of image display devices inconspicuous, it is necessary to narrow the gaps (for example, 100 μm or less), but there are the following problems: in the use environment, the image display device is contracted or expanded, and the gap is slightly increased or the image display device is slightly overlapped, so that the gap is obvious, and the transparency is reduced and the appearance is deteriorated. In addition, there are the following problems: the pressure-sensitive adhesive layer bonded between the optical members constituting the image display device cannot follow the shrinkage and expansion of the image display device, and bulges or peels off at the end portions, thereby deteriorating the appearance.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical adhesive tape used for a tiled display in which a plurality of image display devices are arranged in a tile shape, which makes gaps between the plurality of image display devices less noticeable even in a use environment, and which can maintain transparency and maintain a good appearance.

Means for solving the problems

That is, a first aspect of the present invention provides an optical adhesive tape having a laminated structure in which a base material having a first surface and a second surface and an adhesive layer laminated on the first surface of the base material are laminated.

The optical adhesive tape according to the first aspect of the present invention has an average dimensional change rate in the width direction and the longitudinal direction of within.+ -. 0.15% when heated at 60 ℃ in an environment with a relative humidity of 90% for 500 hours. In a tiled display obtained by arranging a plurality of image display devices in which the optical adhesive tape according to the first aspect of the present invention is laminated, the shrinkage or expansion of the image display devices in the use environment is suppressed, the gaps between the image display devices are suppressed from becoming noticeable, and a good appearance is maintained; the composition having the average dimensional change rate of ±0.15% or less is suitable from the viewpoint of less shrinkage or expansion and maintaining transparency unchanged. The average dimensional change rate is preferably within ±0.1% or less, or may be within ±0.05% from the viewpoint of suppressing the occurrence of significant gaps between image display devices, reducing shrinkage or expansion, and maintaining transparency.

In the optical adhesive tape according to the first aspect of the present invention, the recovery rate of the adhesive layer obtained in the shear test described below is 95% or less.

< shear test >)

The strain A (%) when 500Pa of shear force in 600 seconds of torsion direction was applied from above and below the disk-shaped adhesive layer having a thickness of 2mm and a diameter of 7.9mm at 60℃and the strain B (%) when 1800 seconds was thereafter held at 0Pa of shear force were measured, and the recovery (%) was calculated from the following formula.

Recovery (%) = (strain amount a-strain amount B)/strain amount a×100

In the present specification, when referring to "strain amount a", "strain amount B", and "recovery rate", unless otherwise indicated, "strain amount a", "strain amount B", and "recovery rate" obtained in the above-described shear test are indicated.

The recovery rate of the pressure-sensitive adhesive layer is preferably 95% or less from the viewpoint that the pressure-sensitive adhesive layer can sufficiently follow shrinkage or expansion in the use environment, swelling or peeling can be suppressed, and transparency can be maintained unchanged in the image display device in which the optical pressure-sensitive adhesive tape according to the first aspect of the present invention is laminated. In addition, in the case where there is a level difference in the uneven shape due to wiring or the like on an adherend such as an image display panel, the pressure-sensitive adhesive layer is preferably formed so as to sufficiently follow the level difference and to be capable of filling without leaving bubbles or the like, and the recovery rate of the pressure-sensitive adhesive layer is preferably 95% or less. The recovery rate of the pressure-sensitive adhesive layer is preferably 94% or less, or 93.5% or less, from the viewpoint of suppressing swelling or peeling of the pressure-sensitive adhesive tape for optical use according to the first aspect of the present invention, maintaining the transparency unchanged, and being able to follow the level difference.

The optical adhesive tape according to the first aspect of the present invention preferably satisfies the following formula:

|C×D|≤3

in the above-mentioned method, the step of,

c is the average dimensional change rate [% ] in the width direction and the longitudinal direction when the optical adhesive tape of the first aspect of the present invention is heated at 60℃under an environment of 90% relative humidity for 500 hours,

d is the maximum curl amount [ mm ] of the laminate obtained by bonding the adhesive layer of the optical adhesive tape to a PET film having a thickness of 50 μm and cutting it to 10cm square and heating the laminate at 60℃under a relative humidity of 90% for 500 hours,

maximum curl: the laminate was placed on a horizontal plane with the curled convex surface of the laminate being the lower side, and the highest warpage amount among the 4-angle warpage amounts was set as the maximum curl amount D [ mm ]. The maximum curl amount measured with the laminate placed on a horizontal plane with the PET film side of the laminate being the lower side is set to +, and the maximum curl amount measured with the laminate placed on a horizontal plane with the base material side of the laminate being the lower side is set to +.

In a tiled display obtained by arranging a plurality of image display devices in which the optical adhesive tape according to the first aspect of the present invention is laminated, it is preferable that the absolute value |c×d| of the product of the average dimensional change rate C [% ] and the maximum curl amount D [ mm ] is 3 or less, from the viewpoint that the change in the gap between the image display devices is not easily visually recognized and the image display devices can be bonded to the film substrate with high accuracy. The above |c×d| is preferably 2.5 or less, more preferably 2.4 or less, or may be 2.3 or less or 2.2 or less, from the viewpoint that the change in the gap between the image display devices is not easily visually recognized and the image display devices can be bonded to the film substrate with high accuracy.

In the optical adhesive tape according to the first aspect of the present invention, the strain amount a of the adhesive layer obtained in the shear test is not particularly limited, but is preferably 3% or more. The configuration in which the strain amount a of the pressure-sensitive adhesive layer is 3% or more is preferable from the viewpoint that the pressure-sensitive adhesive layer sufficiently follows shrinkage or expansion in the use environment and can suppress swelling or peeling of the image display device in which the optical pressure-sensitive adhesive tape according to the first aspect of the present invention is laminated. In addition, in the case where there is a level difference in the uneven shape due to wiring or the like on an adherend such as an image display panel, the configuration in which the strain amount a of the adhesive layer is 3% or more is also preferable from the viewpoint that the adhesive layer sufficiently follows the level difference and can be filled without leaving bubbles or the like. The strain amount a of the pressure-sensitive adhesive layer of the present invention is preferably 4% or more, or may be 5% or more, from the viewpoint of suppressing swelling or peeling of the pressure-sensitive adhesive tape for optical use of the present invention and being able to follow a height difference.

In the optical adhesive tape according to the first aspect of the present invention, the strain amount B of the adhesive layer obtained in the shear test is not particularly limited, but is preferably 0.1% or more. The configuration in which the strain amount B of the pressure-sensitive adhesive layer is 0.1% or more is preferable from the viewpoint that the pressure-sensitive adhesive layer sufficiently follows shrinkage or expansion in the use environment and can suppress swelling or peeling of the image display device in which the optical pressure-sensitive adhesive tape according to the first aspect of the present invention is laminated. In addition, in the case where there is a level difference in the uneven shape due to wiring or the like on an adherend such as an image display panel, the configuration in which the strain amount B of the adhesive layer is 0.1% or more is also preferable from the viewpoint that the adhesive layer sufficiently follows the level difference and can be filled without leaving bubbles or the like. The strain amount B of the pressure-sensitive adhesive layer of the present invention is preferably 0.2% or more, or may be 0.3% or more, from the viewpoint of suppressing swelling or peeling of the pressure-sensitive adhesive tape for optical use of the present invention and being able to follow a level difference.

In the optical adhesive tape according to the first aspect of the present invention, the glass transition temperature (Tg) of the base material is preferably 60 ℃ or higher. In a tiled display obtained by arranging a plurality of image display devices in which the optical adhesive tape according to the first aspect of the present invention is laminated, the substrate preferably has a glass transition temperature of 60 ℃ or higher, from the viewpoint of stable mechanical properties of the image display device in a use environment. The glass transition temperature of the substrate may be 63 ℃ or higher or 65 ℃ or higher from the viewpoint of stability of mechanical properties of the image display device.

In the optical adhesive tape according to the first aspect of the present invention, the adhesive layer preferably has a glass transition temperature (Tg) of-10 ℃ or lower. The structure in which the adhesive layer has a Tg of-10 ℃ or lower is preferable from the viewpoints that the stress relaxation property of the adhesive layer is maintained even in a low-temperature environment, the adhesive layer sufficiently follows shrinkage or expansion in the use environment of the image display device in which the optical adhesive tape according to the first aspect of the present invention is laminated, swelling or peeling can be suppressed, and adhesion to an adherend can be sufficiently ensured. The glass transition temperature of the pressure-sensitive adhesive layer is preferably-15 ℃ or lower, or may be-20 ℃ or lower, from the viewpoint of suppressing swelling or peeling in the image display device and good adhesion to an adherend.

The optical adhesive tape according to the first aspect of the present invention preferably has a humidity expansion rate of 0.1% or less when the optical adhesive tape is humidified from 60℃to 30% relative humidity to 60℃and 60% relative humidity. In a tiled display obtained by arranging a plurality of image display devices in which the optical adhesive tape according to the first aspect of the present invention is laminated, it is considered that the expansion of the image display devices due to moisture absorption is suppressed and the gaps between the image display devices are suppressed to be apparent; the above-mentioned composition having a humidity expansion ratio of 0.1% or less is preferable from the viewpoint of less shrinkage or expansion and maintaining transparency unchanged. The humidity expansion ratio is preferably 0.08% or less, or may be 0.06% or less, from the viewpoint of suppressing expansion due to moisture absorption of the image display device, reducing shrinkage or expansion, and maintaining transparency.

In the optical adhesive tape according to the first aspect of the present invention, the substrate preferably has a coefficient of humidity expansion of 5×10 ^-5 The following/%RH. To improve dimensional stability of the substrate upon humidity change; in a tiled display obtained by arranging a plurality of image display devices in which the optical adhesive tape according to the first aspect of the present invention is laminated, the shrinkage or expansion of the image display devices in the use environment is suppressed, and the gaps between the image display devices are suppressed to be apparent, thereby maintaining a good appearance; shrinkage of Or less expansion and can maintain transparency unchanged, the substrate has a coefficient of humidity expansion of 5×10 ^-5 The following/%RH is suitable. The substrate preferably has a coefficient of humidity expansion of 3X 10 from the viewpoint of dimensional stability, less shrinkage or expansion, and maintaining transparency unchanged ^-5 The following/%RH may be 2X 10 ^-5 The following/%RH.

In the optical adhesive tape according to the first aspect of the present invention, the second surface of the base material is preferably subjected to an antireflection treatment and/or an antiglare treatment. The second surface of the base material is preferably subjected to an antireflection treatment and/or an antiglare treatment from the viewpoint of preventing reflection due to metal wiring, ITO wiring, or the like disposed on the substrate of the image display device. In addition, in a tiled display in which a plurality of image display devices in which the optical adhesive tape according to the first aspect of the present invention is laminated are arranged, it is preferable that the second surface of the substrate is subjected to an antireflection treatment and/or an antiglare treatment, because the gaps between the image display devices are not easily visually recognized.

In the optical adhesive tape according to the first aspect of the present invention, the adhesive layer is preferably an acrylic adhesive layer containing an acrylic polymer. This configuration is suitable from the viewpoint of adjusting the above-mentioned properties (in particular, strain amount a, strain amount B, recovery rate) of the pressure-sensitive adhesive layer.

Further, a second aspect of the present invention provides an image display device obtained by laminating the optical adhesive tape of the first aspect of the present invention and an image display panel. Further, a third aspect of the present invention provides a tiled display obtained by arranging a plurality of the image display devices of the second aspect of the present invention.

The image display device according to the second aspect of the present invention has the optical adhesive tape according to the first aspect of the present invention in a laminated structure, and therefore can suppress shrinkage or expansion in a use environment. In addition, even when the image display device according to the second aspect of the present invention is contracted or expanded to some extent, the pressure-sensitive adhesive layer sufficiently follows the contraction or expansion of the image display device, and is less likely to bulge or peel. Therefore, in the tiled display according to the third aspect of the present invention, which is produced by arranging a plurality of image display devices according to the second aspect of the present invention, gaps between the image display devices are less likely to become noticeable in the use environment, and a good appearance can be maintained. In addition, the transparency can be kept unchanged.

Effects of the invention

The optical adhesive tape of the present invention is used for manufacturing a tiled display in which a plurality of image display devices are arranged, and can suppress shrinkage or expansion of the image display devices in the use environment, so that gaps between the image display devices are less likely to be noticeable, and a good appearance can be maintained. In addition, the transparency can be kept unchanged. In addition, even when the image display device expands or contracts to some extent, the pressure-sensitive adhesive layer is less likely to bulge or peel, and thus a high-performance tiled display can be efficiently manufactured.

Drawings

Fig. 1 is a schematic view showing an embodiment of an optical adhesive tape according to the present invention. Fig. 1 (a) is a cross-sectional view, and fig. 1 (b) is a plan view.

Fig. 2 is a schematic view (cross-sectional view) showing another embodiment of the optical adhesive tape of the present invention.

Fig. 3 is a schematic view (cross-sectional view) showing an embodiment of the image display device of the present invention in which the optical adhesive tape of fig. 2 is laminated.

Fig. 4 is a schematic view (perspective view) showing an embodiment of a tiled display according to the present invention.

Fig. 5 is a schematic view (perspective view) for explaining a shear test.

Detailed Description

A first aspect of the present invention provides an optical adhesive tape having a laminated structure in which a base material having a first surface and a second surface and an adhesive layer laminated on the first surface of the base material are laminated.

In this specification, the optical adhesive tape according to the first aspect of the present invention may be referred to as "the optical adhesive tape according to the present invention". In the present specification, the substrate and the pressure-sensitive adhesive layer constituting the optical pressure-sensitive adhesive tape of the present invention are sometimes referred to as "substrate of the present invention" and "pressure-sensitive adhesive layer of the present invention", respectively. In addition, "adhesive tape" includes the meaning of "adhesive sheet". That is, the optical pressure-sensitive adhesive tape of the present invention may be a pressure-sensitive adhesive sheet having a sheet-like form.

A second aspect of the present invention provides an image display device obtained by laminating the optical adhesive tape of the first aspect of the present invention and an image display panel. In this specification, the image display device according to the second aspect of the present invention is sometimes referred to as "the image display device according to the present invention".

Further, a third aspect of the present invention provides a tiled display obtained by arranging a plurality of image display devices of the present invention. In this specification, the tiled display of the third aspect of the present invention is sometimes referred to as "tiled display of the present invention".

Embodiments of the optical pressure-sensitive adhesive tape according to the present invention will be described below with reference to the drawings, but the present invention is not limited thereto and is merely illustrative.

In fig. 1 (a), an optical adhesive tape 10A has a laminated structure in which a base material 1 and an adhesive layer 2 are laminated. The base material 1 has a first face 1a and a second face 1b, and the adhesive layer 2 is laminated on the first face 1a of the base material 1.

In fig. 1 (b), the width direction (TD) and the Machine Direction (MD) of the optical adhesive tape 10A are defined in correspondence with the width direction (TD) and the Machine Direction (MD) of the base material 1.

In fig. 2, the optical adhesive tape 10B has a laminated structure in which a base material 1 and an adhesive layer 2 are laminated. The base material 1 has a first face 1a and a second face 1b, and the adhesive layer 2 is laminated on the first face 1a of the base material 1. The second surface 1b of the substrate 1 is subjected to an antireflection treatment and/or an antiglare treatment 3.

Fig. 3 is a schematic view (cross-sectional view) showing an embodiment of the image display device of the present invention. In fig. 3, the image display device 20 has an image display panel 4 laminated on the adhesive layer 2 of the optical adhesive tape 10B.

Fig. 4 is a schematic view (perspective view) showing an embodiment of a tiled display according to the present invention. In fig. 4, the tiled display 30 is formed by arranging 9 image display devices 20 (laminated structure is not shown) in a 3×3 array in a tile shape on a support substrate 31, and the image display devices 20 are in contact with each other with a gap 32.

Hereinafter, each configuration will be described.

< adhesive tape for optical use >

The term "optical" in the optical adhesive tape according to the present invention refers to use for optical applications, more specifically, to use for manufacturing of products (optical products) using optical members, and the like. Examples of the optical product include an image display device, an input device such as a touch panel, and the like, and the optical product can be suitably used for manufacturing a liquid crystal image display device, a self-luminous image display device (for example, an organic EL (electroluminescence) image display device, and an LED image display device), and the like. In particular, the optical adhesive tape of the present invention is suitable for manufacturing a tiled display in which a plurality of image display devices are arranged in a tile shape.

The optical pressure-sensitive adhesive tape of the present invention is not particularly limited in form as long as the pressure-sensitive adhesive layer of the present invention is laminated on the first surface of the substrate of the present invention. For example, the pressure-sensitive adhesive tape may be a single-sided pressure-sensitive adhesive tape having only one side as a pressure-sensitive adhesive surface, or may be a double-sided pressure-sensitive adhesive tape having both sides as pressure-sensitive adhesive surfaces. In the case where the optical adhesive tape of the present invention is a double-sided adhesive tape, the optical adhesive tape of the present invention may have a configuration in which two adhesive surfaces are provided by the adhesive layer of the present invention, or may have a configuration in which one adhesive surface is provided by the adhesive layer of the present invention and the other adhesive surface is provided by an adhesive layer (other adhesive layer) other than the adhesive layer of the present invention. In the case where the optical adhesive tape of the present invention forms the outermost surface of an optical product, a single-sided adhesive tape is preferable, and in the case where adherends (optical members) are bonded to each other, a double-sided adhesive tape is preferable.

The optical pressure-sensitive adhesive tape of the present invention may have other layers on the surface or between any layers within a range that does not impair the effects of the present invention, for example, a substrate other than the substrate of the present invention, a pressure-sensitive adhesive layer other than the pressure-sensitive adhesive layer of the present invention, an intermediate layer, an undercoat layer, an antistatic layer, a separator, a surface protective film, and the like, in addition to the substrate of the present invention and the pressure-sensitive adhesive layer of the present invention.

When the optical adhesive tape of the present invention is heated at 60℃under a relative humidity of 90% for 500 hours, the average dimensional change rate in the width direction and the longitudinal direction is within.+ -. 0.15%. The dimensional change rate in the width direction and the longitudinal direction was the percentage (%) of the dimensional change amount after heating at 60 ℃ under a relative humidity of 90% for 500 hours, assuming that the initial dimensions in the width direction and the longitudinal direction were 100%, and was calculated by the following formula.

Dimensional change rate (%) = [ (size after heating at 60 ℃ and 90% relative humidity for 500 hours) - (initial size) ]/(initial size) ×100)

For the dimensional change rate (%), "+" indicates expansion, and "-" indicates contraction. The average dimensional change rate in the width direction and the longitudinal direction is an average value of the dimensional change rate in the width direction and the dimensional change rate in the longitudinal direction, and is calculated by the following formula.

Average dimensional change rate (%) = [ (dimensional change rate (%) in the width direction) + (dimensional change rate (%) in the longitudinal direction) ]/2

The size of the optical adhesive tape of the present invention is not particularly limited, and can be generally obtained by measuring the lengths of the ends in the width direction and the longitudinal direction of the optical adhesive tape.

From the viewpoint of suppressing shrinkage or expansion of the image display device of the present invention in the use environment, suppressing gaps between the image display devices from becoming noticeable, and maintaining a good appearance in the tiled display of the present invention; the composition having the average dimensional change rate of ±0.15% or less is preferable from the viewpoint of less shrinkage or expansion and maintaining transparency unchanged. The average dimensional change rate is preferably within ±0.1% or less, or may be within ±0.05% from the viewpoint of suppressing the occurrence of significant gaps between image display devices, reducing shrinkage or expansion, and maintaining transparency.

The average dimensional change rate of the optical adhesive tape of the present invention can be specifically measured by the method of examples described later. The average dimensional change rate of the optical adhesive tape of the present invention can be adjusted by adjusting the type or thickness of the resin constituting the substrate of the present invention, the coefficient of humidity expansion or glass transition temperature of the substrate, the type of resin constituting the adhesive layer of the present invention, the monomer composition, the degree of crosslinking, the elastic modulus, the glass transition temperature, and the like.

The optical adhesive tape of the present invention preferably satisfies the following formula:

|C×D|≤3

in the above-mentioned method, the step of,

c is the average dimensional change rate [% ] in the width direction and in the longitudinal direction when the optical adhesive tape of the present invention is heated at 60℃under an environment of 90% relative humidity for 500 hours,

In a tiled display obtained by arranging a plurality of image display devices in which the optical adhesive tape of the present invention is laminated, it is preferable that the absolute value |c×d| of the product of the average dimensional change rate C [% ] and the maximum curl amount D [ mm ] is 3 or less, from the viewpoint that the change in the gap between the image display devices is not easily visually recognized and the image display devices can be bonded to the film substrate with high accuracy. The above |c×d| is preferably 2.5 or less, more preferably 2.4 or less, and may be 2.3 or less or 2.2 or less, from the viewpoint that the change in the gap between the image display devices is not easily visually recognized and the image display devices can be bonded to the film substrate with high accuracy.

The lower limit of |c×d| is not particularly limited, but may be 0.001 or more as the lower limit is more preferable.

The absolute value |d|mm of the maximum curl amount is not particularly limited, but is preferably 60mm or less, more preferably 55mm or less, and even more preferably 50mm or less, from the viewpoint that the image display device can be bonded to the film substrate with high accuracy in a tiled display obtained by arranging a plurality of image display devices in which the optical adhesive tape of the present invention is laminated.

The lower limit of |d| is not particularly limited, but may be 0.1mm or more as the lower limit is more preferable.

The above-mentioned |c×d| and |d| of the optical adhesive tape of the present invention can be specifically measured by the method of examples described later. The |c×d| and |d| of the optical adhesive tape of the present invention can be adjusted by adjusting the type or thickness of the resin constituting the substrate of the present invention, the coefficient of thermal expansion or glass transition temperature of the substrate, the type of the resin constituting the adhesive layer of the present invention, the monomer composition, the degree of crosslinking, the elastic modulus, the glass transition temperature, and the like.

The optical pressure-sensitive adhesive tape of the present invention preferably has a humidity expansion rate of 0.1% or less when the tape is humidified from 60℃to 30% relative humidity to 60% relative humidity. From the viewpoint of suppressing expansion of the image display device of the present invention due to moisture absorption and suppressing gaps between the image display devices in the tiled display of the present invention; the above-mentioned composition having a humidity expansion ratio of 0.1% or less is preferable from the viewpoint of less shrinkage or expansion and maintaining transparency unchanged. The humidity expansion ratio is preferably 0.08% or less, or may be 0.06% or less, from the viewpoint of suppressing expansion due to moisture absorption, or from the viewpoint of reducing shrinkage or expansion, and maintaining transparency.

The humidity expansion rate of the optical adhesive tape of the present invention can be specifically measured by the method of examples described later. The humidity expansion ratio of the optical adhesive tape of the present invention can be adjusted by adjusting the type or thickness of the resin constituting the substrate of the present invention, the humidity expansion coefficient or glass transition temperature of the substrate, the type of the resin constituting the adhesive layer of the present invention, the monomer composition, the degree of crosslinking, the elastic modulus, the glass transition temperature, and the like.

The ratio of the longitudinal dimensional change rate to the width dimensional change rate (longitudinal dimensional change rate/width dimensional change rate) when the optical adhesive tape of the present invention is heated at 60 ℃ for 500 hours in an environment with a relative humidity of 90%, is not particularly limited, and is preferably 0.5 to 2.0. In this range, in the tiled display according to the present invention, the difference between the dimensional change rates in the width direction and the longitudinal direction of the image display device according to the present invention in the use environment is small, and from the viewpoint of suppressing the gaps between the image display devices from becoming noticeable and maintaining a good appearance; the shrinkage or expansion is small, and the transparency is kept unchanged. The ratio is preferably 0.6 or more and 1.8 or less, or may be 0.7 or more and 1.5 or less from the viewpoint of suppressing the occurrence of significant gaps between image display devices, reducing shrinkage or expansion, and maintaining transparency.

The above ratio (longitudinal dimensional change rate/width dimensional change rate) of the optical adhesive tape of the present invention can be adjusted by adjusting the type or thickness of the resin constituting the substrate of the present invention, the coefficient of thermal expansion or glass transition temperature of the substrate, the manufacturing conditions of the substrate (for example, the temperature, speed, etc. of extrusion molding), the type of the resin constituting the adhesive layer of the present invention, the monomer composition, the degree of crosslinking, the elastic modulus, the glass transition temperature, etc.

The haze of the optical pressure-sensitive adhesive tape of the present invention is not particularly limited, but is preferably 5% or more. The optical adhesive tape of the present invention preferably has a haze of 5% or more, more preferably 6% or more, and even 7% or more, from the viewpoint of preventing reflection due to metal wiring, ITO wiring, or the like disposed on the substrate of the image display panel in the image display device of the present invention, and from the viewpoint that a gap between the image display devices is not easily visually recognized in the tiled display of the present invention. The upper limit of the haze of the optical pressure-sensitive adhesive tape of the present invention is not particularly limited, but is preferably 50% or less, or may be 40% or less or 30% or less, from the viewpoint of visibility of the tiled display of the present invention.

The haze of the optical adhesive tape of the present invention can be measured according to JIS K7136, and specifically, can be measured by a method described in examples described below. The haze of the optical adhesive tape of the present invention can be adjusted by the type or thickness of the resin constituting the substrate of the present invention, the type or thickness of the resin constituting the adhesive layer of the present invention, the antireflection treatment and/or antiglare treatment applied to the substrate surface, and the like.

The reflectivity of the optical adhesive tape of the present invention is not particularly limited, but is preferably 5% or less. The optical adhesive tape of the present invention preferably has a reflectance of 5% or less, more preferably 3% or less, and even 1.5% or less, from the viewpoint of preventing reflection due to metal wiring, ITO wiring, or the like disposed on the substrate of the image display panel in the image display device of the present invention, and from the viewpoint of making it difficult to visually recognize gaps between the image display devices in the tiled display device of the present invention. The lower limit of the reflectance of the optical pressure-sensitive adhesive tape of the present invention is not particularly limited, and may be 0.1% or more or 0.3% or more.

The reflectance of the optical adhesive tape of the present invention can be measured according to JIS K7361-1, specifically, by the method described in examples described later. The reflectivity of the optical adhesive tape of the present invention can be adjusted by the type or thickness of the resin constituting the substrate of the present invention, the type or thickness of the resin constituting the adhesive layer of the present invention, the antireflection treatment and/or antiglare treatment applied to the substrate surface, and the like.

The total light transmittance of the optical adhesive tape of the present invention is not particularly limited, but is preferably 85% or more. The optical pressure-sensitive adhesive tape of the present invention preferably has a total light transmittance of 85% or more, more preferably 88% or more, and still more preferably 90% or more, from the viewpoint of obtaining excellent transparency and excellent appearance of the image display device of the present invention. The upper limit of the total light transmittance of the optical adhesive tape of the present invention is not particularly limited, and may be 95% or less.

The total light transmittance of the optical adhesive tape of the present invention can be measured according to JIS K7361-1. The total light transmittance of the optical adhesive tape of the present invention can be adjusted by the type or thickness of the resin constituting the substrate of the present invention, the type or thickness of the resin constituting the adhesive layer of the present invention, the antireflection treatment and/or antiglare treatment applied to the substrate surface, and the like.

The thickness of the optical pressure-sensitive adhesive tape of the present invention is not particularly limited, and is preferably in the range of 10 μm to 500 μm, more preferably in the range of 20 μm to 300 μm, and most preferably in the range of 30 μm to 200 μm, in view of workability such as dimensional stability, strength, handleability, and laminability.

< substrate >

Examples of the material constituting the substrate of the present invention include glass and plastic films. Examples of the plastic film include: polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); cyclic Olefin Polymers (COP) (for example, trade names "ARTON" (manufactured by JSR corporation), trade names "ZEONOR" (manufactured by japanese patent No. Weng Zhushi), and the like); acrylic resins such as polymethyl methacrylate (PMMA); plastic materials such as Polycarbonate (PC), triacetyl cellulose (TAC), polysulfone, polyarylate, polyether ether ketone (PEEK), polyimide (PI), transparent polyimide (CPI), polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, and ethylene-propylene copolymer, and polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), cyclic Olefin Polymers (COP), polycarbonate (PC), polyether ether ketone (PEEK), and transparent polyimide (CPI), which are excellent in dimensional stability and hardly shrink, are preferable. It should be noted that these plastic materials can be used singly or in combination of two or more. The base material of the present invention is a portion that is attached to an adherend (image display panel or the like) together with an adhesive layer when the optical adhesive tape of the present invention is attached to the adherend. The release liner that is released at the time of use (at the time of attachment) of the optical adhesive tape of the present invention is not included in the "base material".

The substrate of the present invention is a substrate having a film-like (substrate-like) form with a first surface and a second surface. The width direction (TD) and the Machine Direction (MD) of the base material of the present invention are directions defined in the process of producing the base material, for example, the direction in which the film-like extrusion molded body flows after extrusion molding of the raw material resin material is the Machine Direction (MD), and the width direction (TD) is a direction orthogonal to the machine direction.

The substrate of the present invention is not particularly limited as long as it is an optical member constituting the above optical product, and various optical films such as a cover member, a polarizing plate, a phase difference plate and the like are exemplified, and it is preferable to use the substrate as a cover member. In the case where the substrate of the present invention is a cover member, the second surface is, for example, the outermost surface of the optical product.

The glass transition temperature (Tg) of the substrate of the present invention is not particularly limited, but is preferably 60℃or higher. The constitution in which the glass transition temperature of the substrate of the present invention is 60 ℃ or higher is preferable from the viewpoint of the stability of the mechanical properties of the image display device of the present invention in the use environment in the tiled display of the present invention. The glass transition temperature of the substrate may be 63 ℃ or higher or 65 ℃ or higher from the viewpoint of stability of mechanical properties of the image display device of the present invention. The upper limit of the glass transition temperature of the base material is not particularly limited, and the glass transition temperature of the base material is preferably 350 ℃ or lower, but may be 250 ℃ or lower, 200 ℃ or lower, 140 ℃ or lower, 130 ℃ or lower, or 125 ℃ or lower, from the viewpoint of simplifying the molding process of the base material.

The glass transition temperature (Tg) of the substrate of the present invention can be measured according to JIS K7121. The glass transition temperature (Tg) of the substrate of the present invention can be adjusted by the kind of resin constituting the substrate of the present invention, and the like.

The substrate of the present invention is not particularly limited in the coefficient of humidity expansion, and is preferably 5X 10 ^-5 The following/%RH. Dimensional stability upon humidity change from the substrate of the present invention is improved; in the tiled display of the present invention, the shrinkage or expansion of the image display device of the present invention under the use environment is suppressed, and the gap between the image display devices is suppressed from becoming noticeable, thereby maintaining a good appearance; the substrate of the present invention has a coefficient of humidity expansion of 5×10 from the viewpoint of less shrinkage or expansion and being capable of maintaining transparency unchanged ^-5 The following/%RH is suitable. The substrate of the present invention preferably has a coefficient of humidity expansion of 3×10 from the viewpoint of dimensional stability, less shrinkage or expansion, and the ability to maintain transparency unchanged ^-5 The following/%RH may be 2X 10 ^-5 The following/%RH.

The lower limit of the coefficient of humidity expansion of the substrate of the present invention is not particularly limited, and the lower the coefficient, the more preferable the coefficient, and may be 0.001X 10 ^-5 above/%RH.

The coefficient of humidity expansion of the substrate of the present invention can be specifically measured by the method described in examples described later. The coefficient of humidity expansion of the substrate of the present invention can be adjusted by the type of resin constituting the substrate of the present invention, the conditions (temperature, extrusion speed, etc.) at the time of substrate production, and the like.

The haze of the substrate of the present invention is not particularly limited, but is preferably 5% or more. The substrate of the present invention preferably has a haze of 5% or more, more preferably 6% or more, and still more preferably 7% or more, from the viewpoint of preventing reflection due to metal wiring, ITO wiring, or the like disposed on the substrate of the image display panel of the present invention, and from the viewpoint of making it difficult to visually recognize gaps between the image display devices in the tiled display of the present invention. The upper limit of the haze of the substrate of the present invention is not particularly limited, but is preferably 50% or less, or may be 40% or less or 30% or less, from the viewpoint of visibility of the tiled display of the present invention.

The haze of the substrate of the present invention can be measured according to JIS K7136. The haze of the substrate of the present invention can be adjusted by the type or thickness of the resin constituting the substrate of the present invention, by subjecting the surface of the substrate to an antireflection treatment and/or an antiglare treatment, and the like.

The reflectance of the substrate of the present invention is not particularly limited, but is preferably 5% or less. The substrate of the present invention preferably has a reflectance of 5% or less, more preferably 3% or less, and even more preferably 1.5% or less, from the viewpoint of preventing reflection due to metal wiring, ITO wiring, or the like disposed on the substrate of the image display panel of the present invention, and from the viewpoint of making it difficult to visually recognize gaps between the image display devices in the tiled display of the present invention. The lower limit of the reflectance of the substrate of the present invention is not particularly limited, and may be 0.1% or more or 0.3% or more.

The reflectance of the substrate of the present invention can be measured according to JIS K7361-1. The reflectivity of the substrate of the present invention can be adjusted by the type or thickness of the resin constituting the substrate of the present invention, by subjecting the surface of the substrate to an antireflection treatment and/or an antiglare treatment, and the like.

The thickness of the substrate of the present invention is not particularly limited, and is preferably in the range of 10 μm to 500 μm, more preferably in the range of 20 μm to 300 μm, and most preferably in the range of 30 μm to 200 μm, in view of workability such as dimensional stability, strength, workability, and laminability. The refractive index of the substrate of the present invention is not particularly limited, and is, for example, in the range of 1.30 to 1.80, preferably in the range of 1.40 to 1.70.

The second side of the substrate of the present invention is preferably subjected to an antireflection treatment and/or an antiglare treatment. The second surface of the substrate of the present invention is preferably subjected to an antireflection treatment and/or an antiglare treatment from the viewpoint of being able to prevent reflection due to metal wiring, ITO wiring, or the like disposed on the substrate of the image display device of the present invention. In addition, from the viewpoint that the gap between the image display devices is not easily visually recognized in the tiled display of the present invention, it is also preferable that the second surface of the substrate of the present invention is subjected to an antireflection treatment and/or an antiglare treatment.

The antireflection treatment may be any known antireflection treatment without particular limitation, and examples thereof include an Antireflection (AR) treatment.

The anti-reflection (AR) treatment may be applied without particular limitation to a known AR treatment, and specifically, may be performed by forming an optical film having a strictly controlled thickness and refractive index on the second surface of the substrate of the present invention or by laminating two or more of the above optical films to form an anti-reflection layer (AR layer). The AR layer exhibits an antireflection function by canceling the inverted phases of incident light and reflected light from each other by the interference effect of light. The AR layer is preferably designed to have a wavelength range of visible light exhibiting an antireflection function, for example, 380nm to 780nm, particularly a wavelength range of 450nm to 650nm, which is a wavelength range of high visual acuity, and to minimize a reflectance of 550nm as its center wavelength.

As the AR layer, a multilayer antireflection layer having a structure in which 2 to 5 optical thin layers (thin films whose thickness and refractive index are strictly controlled) are laminated is generally used, and by forming a plurality of components having different refractive indexes at a predetermined thickness, the degree of freedom in optical design of the AR layer is improved, the antireflection effect can be further improved, and the spectral reflection characteristics can be made uniform (flattened) in the visible light region. In the optical film, since high thickness accuracy is required, formation of each layer is generally performed by dry vacuum deposition, sputtering, CVD, or the like.

The AR layer may be formed using an antireflection layer-forming coating liquid. The coating liquid for forming an antireflection layer may contain, for example, a resin, an additive containing a fluorine element, hollow particles, solid particles, a diluting solvent, and the like, and can be produced by mixing them.

Examples of the resin include: a thermosetting resin, and an ionizing radiation curable resin cured by ultraviolet rays or light. As the resin, a commercially available thermosetting resin, an ultraviolet curable resin, or the like can be used.

Examples of the thermosetting resin and the ultraviolet curable resin include curable compounds having at least one of an acrylate group and a methacrylate group, which are cured by heat, light (ultraviolet rays, etc.), electron beam, or the like: oligomers or prepolymers of acrylates or methacrylates of polyfunctional compounds such as silicone resins, polyester resins, polyether resins, epoxy resins, polyurethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, polyols, and the like. One kind of them may be used alone, or two or more kinds may be used in combination.

For example, a reactive diluent having at least one of an acrylate group and a methacrylate group can be used as the resin. As the reactive diluent, for example, those described in japanese patent application laid-open No. 2008-88309 can be used, and examples thereof include monofunctional acrylates, monofunctional methacrylates, polyfunctional acrylates, polyfunctional methacrylates, and the like. The reactive diluent is preferably a trifunctional or higher acrylate or a trifunctional or higher methacrylate. This is because the hardness of the second surface of the substrate of the present invention can be made excellent. Examples of the reactive diluent include: butanediol glycerol ether diacrylate, isocyanuric acid acrylate, isocyanuric acid methacrylate, and the like. One kind of them may be used alone, or two or more kinds may be used in combination. The weight average molecular weight of the resin before curing may be, for example, 100 or more, 300 or more, 500 or more, 1,000 or more, or 2,000 or more, and may be 100,000 or less, 70,000 or less, 50,000 or less, 30,000 or less, or 10,000 or less. If the weight average molecular weight before curing is high, the hardness is lowered, but cracks tend not to be generated easily at the time of bending. On the other hand, if the weight average molecular weight before curing is low, the intermolecular crosslink density tends to be high and the hardness tends to be high.

The resin preferably contains a polyfunctional acrylate (for example, pentaerythritol triacrylate).

For curing the curable resin, a curing agent may be added, for example. The curing agent is not particularly limited, and for example, a known polymerization initiator (e.g., a thermal polymerization initiator, a photopolymerization initiator, etc.) can be suitably used. The amount of the curing agent to be added is not particularly limited, but may be, for example, 0.5 parts by weight or more, 1.0 parts by weight or more, 1.5 parts by weight or more, 2.0 parts by weight or more, or 2.5 parts by weight or more, 15 parts by weight or less, 13 parts by weight or less, 10 parts by weight or less, 7 parts by weight or less, or 5 parts by weight or less, based on 100 parts by weight of the resin in the coating liquid for forming an antireflection layer.

The additive containing fluorine is not particularly limited, and may be, for example, an organic compound or an inorganic compound containing fluorine in the molecule. The organic compound is not particularly limited, and examples thereof include: fluorine-containing antifouling coating agents, fluorine-containing acrylic compounds, fluorine-and silicon-containing acrylic compounds, and the like. Specific examples of the organic compound include: trade names "KY-1203" manufactured by Xinyue chemical industry Co., ltd., trade name "MEGAFACE" manufactured by DIC Co., ltd. The inorganic compound is also not particularly limited. The amount of the fluorine-containing additive to be added is not particularly limited, and for example, the amount of the fluorine element in the solid content may be, for example, 0.05 wt% or more, 0.1 wt% or more, 0.15 wt% or more, 0.20 wt% or more, or 0.25 wt% or more, and may be 20 wt% or less, 15 wt% or less, 10 wt% or less, 5 wt% or less, or 3 wt% or less, based on the total weight of the solid content in the coating liquid for forming an antireflection layer. For example, the amount of the fluorine-containing additive may be, for example, 0.05 wt% or more, 0.1 wt% or more, 0.15 wt% or more, 0.20 wt% or more, or 0.25 wt% or more, and may be 20 wt% or less, 15 wt% or less, 10 wt% or less, 5 wt% or 3 wt% or less, based on 100 parts by weight of the resin in the coating liquid for forming an antireflection layer.

The hollow particles are not particularly limited, and may be, for example, silica particles, acrylic polymer particles, acrylic-styrene copolymer particles, or the like. Examples of the silica particles include: trade names "THRULYA 5320", "THRULYA 4320", etc. manufactured by the Nisshua catalyst chemical industry Co. The weight average particle diameter of the hollow particles is not particularly limited, and may be, for example, 30nm or more, 40nm or more, 50nm or more, 60nm or more, or 70nm or more, and may be 150nm or less, 140nm or less, 130nm or less, 120nm or less, or 110nm or less. The hollow particles may be, for example, spherical particles, or irregularly shaped particles such as powder, and are preferably spherical particles, more preferably spherical particles having an aspect ratio of 1.5 or less, and most preferably spherical particles. By adding the hollow particles, for example, the antireflection layer can have a low refractive index and excellent antireflection characteristics. The amount of the hollow particles to be added is not particularly limited, and may be, for example, 30 parts by weight or more, 50 parts by weight or more, 70 parts by weight or more, 90 parts by weight or more, or 100 parts by weight or more, 300 parts by weight or less, 270 parts by weight or less, 250 parts by weight or less, 200 parts by weight or less, or 180 parts by weight or less, based on 100 parts by weight of the resin in the coating liquid for forming an antireflection layer. The amount of the hollow particles to be added is preferably not too large from the viewpoint of lowering the refractive index of the antireflection layer, and the amount of the hollow particles to be added is preferably not too large from the viewpoint of securing the mechanical properties of the antireflection layer.

The solid particles are not particularly limited, and may be, for example, silica particles, zirconia particles, titanium-containing particles (for example, titanium oxide particles), or the like. Examples of the silica particles include: trade names "MEK-2140Z-AC", "MIBK-ST", "IPA-ST", etc. manufactured by Nissan chemical Co., ltd. The weight average particle diameter of the solid particles is not particularly limited, and may be, for example, 5nm or more, 10nm or more, 15nm or more, 20nm or more, or 25nm or more, and may be 300nm or less, 250nm or less, 200nm or less, 150nm or less, or 100nm or less. The shape of the solid particles is not particularly limited, and may be, for example, a bead-like approximately spherical shape, or may be an irregularly shaped particle such as a powder, and is preferably an approximately spherical particle, more preferably an approximately spherical particle having an aspect ratio of 1.5 or less, and most preferably a spherical particle. By adding the solid particles, the fluorine-containing additive is easily concentrated on the surface of the applied coating liquid for forming an antireflection layer, and the antireflection layer is excellent in scratch resistance, and can realize a low refractive index, good antireflection characteristics, and the like. The amount of the solid particles to be added is not particularly limited, and may be, for example, 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, or 25 parts by weight or more, and 150 parts by weight or less, 120 parts by weight or less, 100 parts by weight or less, or 80 parts by weight or less, based on 100 parts by weight of the resin in the coating liquid for forming an antireflection layer.

The diluent solvent may be, for example, a mixed solvent containing MIBK (methyl isobutyl ketone) and PMA (propylene glycol monomethyl ether acetate). The mixing ratio in this case is not particularly limited, and when the weight of MIBK is 100 wt%, the weight of PMA may be, for example, 20 wt% or more, 50 wt% or more, 100 wt% or more, 150 wt% or more, or 200 wt% or more, and may be 400 wt% or less, 350 wt% or less, 300 wt% or less, or 250 wt% or less.

The diluent solvent may be, for example, a mixed solvent containing TBA (t-butanol) in addition to MIBK and PMA. The mixing ratio in this case is not particularly limited, and when the weight of MIBK is 100 wt%, the weight of PMA may be, for example, 10 wt% or more, 30 wt% or more, 50 wt% or more, 80 wt% or more, or 100 wt% or more, and may be 200 wt% or less, 180 wt% or less, 150 wt% or less, 130 wt% or less, or 110 wt% or less. When the weight of MIBK is set to 100 wt%, the weight of TBA may be, for example, 10 wt% or more, 30 wt% or more, 50 wt% or more, 80 wt% or more, or 100 wt% or more, and 200 wt% or less, 180 wt% or less, 150 wt% or less, 130 wt% or less, or 110 wt% or less.

The addition amount of the diluting solvent is not particularly limited, and may be, for example, 0.1 wt% or more, 0.3 wt% or more, 0.5 wt% or more, 1.0 wt% or more, or 1.5 wt% or more, based on the weight of the entire coating liquid for forming an antireflection layer, or may be 20 wt% or less, 15 wt% or less, 10 wt% or less, 5 wt% or less, or 3 wt% or less, based on the weight of the entire coating liquid for forming an antireflection layer. The content of the solid component is preferably not high from the viewpoint of securing coatability (wetting and leveling), and not low from the viewpoint of preventing appearance defects caused by drying, such as air-drying spots and whitening.

Next, the coating liquid for forming an antireflection layer is coated on the second surface of the substrate of the present invention (the coating step). The coating method is not particularly limited, and for example, a known coating method such as a spray coating method, a die coating method, a spin coating method, a spray coating method, a gravure coating method, a roll coating method, or a bar coating method can be suitably used. The coating amount of the coating liquid for forming an antireflection layer is not particularly limited, and the thickness of the formed antireflection layer may be, for example, 0.1 μm or more, 0.3 μm or more, 0.5 μm or more, 1.0 μm or more, or 2.0 μm or more, and the thickness of the formed antireflection layer may be 50 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, or 10 μm or less.

Next, the applied coating liquid for forming the antireflection layer is dried to form a coating film (the coating film forming step). The drying temperature is not particularly limited, and may be, for example, in the range of 30℃to 200 ℃. The drying temperature may be, for example, 40℃or more, 50℃or more, 60℃or more, 70℃or more, 80℃or more, 90℃or more, or 100℃or more, and may be 190℃or less, 180℃or less, 170℃or less, 160℃or less, 150℃or less, 140℃or less, 135℃or less, 130℃or less, 120℃or less, or 110 ℃. The drying time is not particularly limited, and may be, for example, 30 seconds or more, 40 seconds or more, 50 seconds or more, or 60 seconds or more, and may be 150 seconds or less, 130 seconds or less, 110 seconds or less, or 90 seconds or less.

In addition, the coating film may be cured (curing step). The curing can be performed by heating, light irradiation, or the like, for example. The light is not particularly limited, and may be, for example, ultraviolet rays. The light source for the light irradiation is not particularly limited, and may be, for example, a high-pressure mercury lamp. The irradiation amount of the energy ray source in the ultraviolet curing is preferably 50mJ/cm in terms of cumulative exposure amount at 365nm of ultraviolet wavelength ² ～500mJ/cm ² . If the irradiation amount is 50mJ/cm ² As described above, curing is easily and sufficiently performed, and the hardness of the formed antireflection layer is easily increased. In addition, if the irradiation amount is 500mJ/cm ² The coloring of the formed antireflection layer can be prevented.

The Antiglare (AG) treatment can be applied to a known AG treatment without any particular limitation, and can be performed by forming an antiglare layer on the second surface of the substrate of the present invention. The antiglare layer may be any known antiglare layer, and is usually formed as a layer in which inorganic particles or organic particles as an antiglare agent are dispersed in a resin.

The antiglare layer is not particularly limited, and is formed using, for example, an antiglare layer-forming material containing a resin, particles, and a thixotropic agent, and convex portions are formed on the surface of the antiglare layer by aggregation of the particles and the thixotropic agent. According to this configuration, the antiglare layer has excellent display characteristics, i.e., both antiglare properties and white blur prevention, and even when the antiglare layer is formed by aggregation of particles, the occurrence of protrusions on the surface of the antiglare layer, which are appearance defects, can be prevented, and the yield of the product can be improved.

Examples of the resin include: a thermosetting resin; an ionizing radiation curable resin cured by ultraviolet rays or light. As the resin, a commercially available thermosetting resin, an ultraviolet curable resin, or the like can be used.

Examples of the thermosetting resin and the ultraviolet curable resin include curable compounds having at least one of an acrylate group and a methacrylate group, which are cured by heat, light (ultraviolet rays, etc.), electron beam, or the like: oligomers or prepolymers of acrylates, methacrylates, and the like of polyfunctional compounds such as silicone resins, polyester resins, polyether resins, epoxy resins, polyurethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, polyols, and the like. One kind of them may be used alone, or two or more kinds may be used in combination.

Reactive diluents having at least one of an acrylate group and a methacrylate group, for example, can also be used in the above resin. As the reactive diluent, for example, the reactive diluent described in japanese patent application laid-open No. 2008-88309 can be used, and examples thereof include monofunctional acrylates, monofunctional methacrylates, polyfunctional acrylates, polyfunctional methacrylates, and the like. The reactive diluent is preferably a trifunctional or higher acrylate or a trifunctional or higher methacrylate. This is because the antiglare layer can be made excellent in hardness. Examples of the reactive diluent include: butanediol glycerol ether diacrylate, isocyanuric acid acrylate, isocyanuric acid methacrylate, and the like. One kind of them may be used alone, or two or more kinds may be used in combination.

The resin is preferably a copolymer containing a urethane acrylate resin, more preferably a curable urethane acrylate resin and a polyfunctional acrylate (for example, pentaerythritol triacrylate).

The particles for forming the antiglare layer have a main function of imparting antiglare properties to the surface of the antiglare layer to be formed into a concave-convex shape and controlling the haze value of the antiglare layer. The haze value of the antiglare layer can be designed by controlling the refractive index difference between the particles and the resin. Examples of the particles include inorganic particles and organic particles. The inorganic particles are not particularly limited, and examples thereof include: silica particles, titanium oxide particles, aluminum oxide particles, zinc oxide particles, tin oxide particles, zirconium oxide particles, calcium carbonate particles, barium sulfate particles, talc particles, kaolin particles, calcium sulfate particles, and the like. The organic particles are not particularly limited, and examples thereof include: polymethyl methacrylate resin powder (PMMA microparticles), silicone resin powder, polystyrene resin powder, polycarbonate resin powder, acrylic-styrene resin powder, phenylguanamine resin powder, melamine resin powder, polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, polyfluorene resin powder, and the like. These inorganic particles and organic particles may be used singly or in combination of two or more.

The weight average particle diameter (D) of the particles is preferably in the range of 2.5 μm to 10. Mu.m. By setting the weight average particle diameter of the particles in the above range, for example, antiglare properties are more excellent, and white blurring can be prevented. The weight average particle diameter of the particles is more preferably in the range of 3 μm to 7. Mu.m. The weight average particle diameter of the particles can be measured by, for example, the coulter counter method. For example, the number and volume of particles are measured by measuring the resistance of an electrolyte corresponding to the volume of the particles when the particles pass through the pores using a particle size distribution measuring apparatus (trade name: coulter Multisizer, manufactured by Beckmann Kort Co., ltd.) by a pore resistance method, and the weight average particle diameter is calculated.

The shape of the particles is not particularly limited, and may be, for example, a bead-like approximately spherical shape, or may be an irregularly shaped particle such as a powder, and is preferably an approximately spherical particle, more preferably an approximately spherical particle having an aspect ratio of 1.5 or less, and most preferably a spherical particle.

The proportion of the particles in the antiglare layer is preferably in the range of 0.2 to 12 parts by weight, more preferably in the range of 0.5 to 12 parts by weight, and even more preferably in the range of 1 to 7 parts by weight, relative to 100 parts by weight of the resin. By setting in the above range, for example, antiglare properties are more excellent, and white blurring can be prevented.

The antiglare layer described above may include a thixotropic agent. By including the thixotropic agent, the aggregation state of the particles can be easily controlled. Examples of the thixotropic agent for forming the antiglare layer include: organoclay, oxidized polyolefin, modified urea, and the like.

The organoclay is preferably an organized clay which is subjected to an improvement in affinity with the resin. Examples of organoclays include: layered organoclay. The organoclay may be self-made or commercially available. Examples of the commercial products include: lucentite SAN, lucentite STN, lucentite SEN, lucentite SPN, somasif ME-100, somasif MAE, somasif MTE, somasif MEE, somasif MPE (trade name, all manufactured by Co-op Chemical company); esben, esben C, esben E, esben W, esben P, esben WX, esben N-400, esben NX80, esben NO12S, esben NEZ, esben NO12, esben NE, esben NZ70, organic D, organic T (trade name, all manufactured by Hojun Co., ltd.); kunipia F, kunipia G4 (trade names, all manufactured by Kunimine industrial co.); thixogel VZ, clayton HT, clayton 40 (trade name, manufactured by Rockwood Additives company), and the like.

The oxidized polyolefin may be self-made or commercially available. Examples of the commercial products include: disparon 4200-20 (trade name, manufactured by Nanyu chemical Co., ltd.), flonon SA300 (trade name, manufactured by Kyowa chemical Co., ltd.), and the like.

The modified urea is the reaction product of an isocyanate monomer or an adduct thereof and an organic amine. The modified urea may be self-made or commercially available. Examples of the commercial products include: BYK410 (manufactured by pick chemical company), and the like.

The thixotropic agent may be used alone or in combination of two or more.

The height of the convex portion from the roughness average line of the antiglare layer is preferably less than 0.4 times the thickness of the antiglare layer. More preferably in the range of 0.01 times or more and 0.4 times or less, and still more preferably in the range of 0.01 times or more and 0.3 times or less. If the amount is within this range, the formation of a protrusion, which is an appearance defect, on the convex portion can be prevented appropriately. The antiglare layer can be less likely to cause appearance defects by the convex portion having such a height. The height from the roughness average line can be measured by the method described in, for example, japanese patent application laid-open No. 2017-138620.

The proportion of the thixotropic agent in the antiglare layer is preferably in the range of 0.1 to 5 parts by weight, more preferably in the range of 0.2 to 4 parts by weight, relative to 100 parts by weight of the resin.

The thickness (d) of the antiglare layer is not particularly limited, but is preferably in the range of 3 μm to 12 μm. By setting the thickness (d) of the antiglare layer within the above range, for example, curling of the optical adhesive tape of the present invention can be prevented from occurring, and the problem of productivity degradation such as poor transportation can be avoided. In the case where the thickness (D) is within the above range, the weight average particle diameter (D) of the particles is preferably within the range of 2.5 μm to 10 μm as described above. The antiglare property can be further improved by combining the thickness (D) of the antiglare layer and the weight average particle diameter (D) of the particles. The thickness (d) of the antiglare layer is more preferably in the range of 3 μm to 8 μm.

The relation between the thickness (D) of the antiglare layer and the weight average particle diameter (D) of the particles is preferably in the range of 0.3.ltoreq.D/d.ltoreq.0.9. By satisfying such a relationship, an antiglare layer which is more excellent in antiglare properties, can prevent white blushing, and has no appearance defects can be formed.

In the optical adhesive tape according to the present invention, as described above, the anti-glare layer is formed with convex portions on the surface of the anti-glare layer by aggregation of the particles and the thixotropic agent. In the aggregated portion forming the convex portion, the particles are present in a state in which a plurality of particles are aggregated in the surface direction of the antiglare layer. Thereby, the convex portion has a gentle shape. The antiglare layer can maintain antiglare properties, prevent white blushing, and prevent appearance defects by the convex portion having such a shape.

The surface shape of the antiglare layer can be arbitrarily designed by controlling the aggregation state of particles contained in the antiglare layer forming material. The aggregation state of the particles can be controlled by, for example, the material of the particles (for example, the chemically modified state of the particle surface, affinity for a solvent or a resin, etc.), the resin (binder), the kind and combination of solvents, and the like. Here, the aggregation state of the particles can be controlled by the thixotropic agent contained in the antiglare layer forming material. As a result, the aggregation state of the particles can be set as described above, and the convex portion can be formed in a gentle shape.

In the optical adhesive tape of the present invention, when the substrate of the present invention is formed of a resin or the like, it is preferable that the substrate of the present invention has a permeation layer at the interface with the antiglare layer. The above-mentioned permeation layer is formed by permeation of the resin component contained in the above-mentioned antiglare layer forming material into the base material of the present invention. When the permeation layer is formed, it is preferable that the adhesion between the base material of the present invention and the antiglare layer is improved. The thickness of the above-mentioned permeation layer is preferably in the range of 0.2 μm to 3. Mu.m, more preferably in the range of 0.5 μm to 2. Mu.m. For example, in the case where the base material of the present invention is a polyester resin and the resin contained in the antiglare layer is an acrylic resin, the permeation layer can be formed. The above-mentioned permeation layer can be confirmed and the thickness can be measured by observing the cross section of the optical adhesive tape of the present invention by using a Transmission Electron Microscope (TEM), for example.

Even when applied to the optical adhesive tape of the present invention having such a permeation layer, a desired gentle surface roughness having both antiglare properties and white blur prevention can be easily formed. The substrate having poor adhesion to the antiglare layer is preferably formed thicker in order to improve adhesion.

In the above anti-glare layer, it is preferable that the thickness of the layer is 1m ² The antiglare layer of (2) has 1 or less appearance defects having a maximum diameter of 200 [ mu ] m or more. More preferably, the above-mentioned appearance defects are not present.

In the uneven shape of the antiglare layer surface, the average inclination angle θa (°) is preferably in the range of 0.1 to 5.0, more preferably in the range of 0.3 to 4.5, still more preferably in the range of 1.0 to 4.0, and particularly preferably in the range of 1.6 to 4.0. Here, the average inclination angle θa is a value defined by the following formula (1). The average inclination angle θa is a value measured by a method described in, for example, japanese patent application laid-open No. 2017-138620.

Average tilt angle θa=tan-1 Δa (1)

In the above formula (1), Δa is a value obtained by dividing the sum (h1+h2+h … … +hn) of the differences (height h) between the peaks and the bottoms of the adjacent peaks in the reference length L of the roughness curve defined in JIS B0601 (published 1994) by the reference length L, as shown in the following formula (2). The roughness curve is a curve obtained by removing a surface ripple component longer than a predetermined wavelength from a cross-sectional curve by a phase difference compensation type high-pass filter. The cross-sectional curve is a contour that appears in a notch when the object surface is cut by a plane perpendicular to the object surface.

Δa＝(h1+h2+h3……+hn)/L (2)

When θa is in the above range, antiglare properties are more excellent, and white blurring can be prevented.

In forming the antiglare layer, the antiglare layer-forming material (coating liquid) prepared preferably exhibits thixotropic properties, and the below-specified Ti value is preferably in the range of 1.3 to 3.5, more preferably in the range of 1.3 to 2.8.

Ti value = β1/β2

Here, β1 is the viscosity measured using rhestruss 6000 manufactured by HAAKE company under the condition of a shear rate of 20 (1/s), and β2 is the viscosity measured using rhestruss 6000 manufactured by HAAKE company under the condition of a shear rate of 200 (1/s).

When the Ti value is less than 1.3, appearance defects are likely to occur, and antiglare properties and white blur properties are deteriorated. When the Ti value is more than 3.5, the particles are less likely to aggregate and tend to be dispersed.

The method for producing the antiglare layer is not particularly limited, and the antiglare layer can be produced by any method, for example, the following method is applicable: an antiglare layer-forming material (coating liquid) containing the resin, the particles, the thixotropic agent, and the solvent is prepared, the antiglare layer-forming material (coating liquid) is applied onto the second surface of the substrate of the present invention to form a coating film, and the coating film is cured to form an antiglare layer. A transfer method using a mold, a method of imparting a concave-convex shape by a suitable method such as sandblasting or embossing rollers, or the like may be used together.

The solvent is not particularly limited, and various solvents may be used, and one may be used alone or two or more may be used in combination. Depending on the composition of the resin, the types and contents of the particles and the thixotropic agent, there are optimum solvent types and solvent ratios. The solvent is not particularly limited, and examples thereof include: alcohols such as methanol, ethanol, isopropanol, butanol, and 2-methoxyethanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and the like; esters such as methyl acetate, ethyl acetate, and butyl acetate; ethers such as diisopropyl ether and propylene glycol monomethyl ether; glycols such as ethylene glycol and propylene glycol; cellosolves such as ethyl cellosolve and butyl cellosolve; aliphatic hydrocarbons such as hexane, heptane, octane, etc.; aromatic hydrocarbons such as benzene, toluene and xylene.

For example, when a polyester resin is used as the base material of the present invention and the permeation layer is formed, a good solvent for the polyester resin can be suitably used. Examples of the solvent include: ethyl acetate, methyl ethyl ketone, cyclopentanone, and the like.

By properly selecting the solvent, thixotropic properties of the anti-glare layer forming material (coating liquid) can be favorably exhibited by the thixotropic agent. For example, in the case of using organoclay, toluene and xylene can be used alone or in combination as appropriate, for example, in the case of using oxidized polyolefin, methyl ethyl ketone, ethyl acetate, propylene glycol monomethyl ether can be used alone or in combination as appropriate, for example, in the case of using modified urea, butyl acetate and methyl isobutyl ketone can be used alone or in combination as appropriate.

Various leveling agents can be added to the antiglare layer forming material. As the leveling agent, for example, a fluorine-containing leveling agent or a silicone leveling agent can be used to prevent uneven coating (leveling of the coated surface). The leveling agent can be appropriately selected depending on the case where antifouling property is required on the surface of the antiglare layer, the case where an antireflection layer (low refractive index layer) or a layer containing an interlayer filler is formed on the antiglare layer, or the like. For example, by containing the thixotropic agent, the coating liquid can exhibit thixotropic properties, and thus coating unevenness is less likely to occur. Thus, for example, there is an advantage in expanding the options of the leveling agent described above.

The amount of the leveling agent to be blended is, for example, 5 parts by weight or less, and preferably in the range of 0.01 to 5 parts by weight, based on 100 parts by weight of the resin.

The anti-glare layer forming material may contain pigments, fillers, dispersants, plasticizers, ultraviolet absorbers, surfactants, antifouling agents, antioxidants, and the like as necessary within a range that does not impair the performance. These additives may be used singly or in combination of two or more.

For example, a conventionally known photopolymerization initiator as described in japanese patent application laid-open No. 2008-88309 can be used as the antiglare layer forming material.

As a method of applying the anti-glare layer forming material to the second surface of the substrate of the present invention, for example, a coating method such as a spray coating method, a die coating method, a spin coating method, a spray coating method, a gravure coating method, a roll coating method, or a bar coating method can be used.

The anti-glare layer forming material is coated to form a coating film on the substrate of the present invention, and the coating film is cured. The coating film is preferably dried before the curing. The drying may be, for example, natural drying, air drying by blowing, heating drying, or a combination thereof.

The method for curing the coating film of the antiglare layer-forming material is not particularly limited, and ultraviolet curing is preferable. The irradiation amount of the energy ray source is preferably 50mJ/cm in terms of cumulative exposure amount at 365nm of ultraviolet wavelength ² ～500mJ/cm ² . If the irradiation amount is 50mJ/cm ² As described above, the curing becomes more sufficient, and the hardness of the formed antiglare layer becomes more sufficient. In addition, if the irradiation amount is 500mJ/cm ² The coloring of the formed antiglare layer can be prevented as follows.

The antiglare layer described above can be formed on the second surface of the substrate of the present invention in the above manner. The antiglare layer may be formed by a manufacturing method other than the above method. The hardness of the antiglare layer is also affected by the thickness of the layer, but it is preferable to have a hardness of 2H or more in terms of pencil hardness.

The antiglare layer may have a multilayer structure in which two or more layers are stacked.

The AR layer (low refractive index layer) may be disposed on the antiglare layer. For example, when the optical adhesive tape is mounted on an image display device, reflection of light at the interface between air and an antiglare layer is one of the main causes of lowering visibility of an image. The AR layer reduces this surface reflection. The antiglare layer and the antireflection layer may each have a multilayer structure in which two or more layers are stacked.

In order to prevent the adhesion of contaminants and to improve the ease of removal of the attached contaminants, it is preferable to laminate an anti-contamination layer made of a fluorine-containing silane compound, a fluorine-containing organic compound, or the like on the anti-reflection layer and/or the anti-glare layer.

It is preferable to subject at least one of the base material of the present invention and the antiglare layer to surface treatment. If the surface of the substrate of the present invention is subjected to a surface treatment, the adhesion to the antiglare layer is further improved. In addition, if the surface of the antiglare layer is subjected to surface treatment, the adhesion to the AR layer is further improved.

In order to prevent curling of the base material of the present invention, the other surface of the antiglare layer may be subjected to a solvent treatment. In order to prevent curling, a transparent resin layer may be formed on the other surface of the antiglare layer.

< adhesive layer >)

The adhesive layer of the present invention may be an adhesive layer having no base material (base material layer), or may be an adhesive layer having a base material. In the present specification, an adhesive layer having no base material (base material layer) is sometimes referred to as a "base material-free adhesive layer", and an adhesive layer having a base material type is sometimes referred to as a "base material-attached adhesive layer". Examples of the substrate-free adhesive layer include: a single-layer adhesive layer including only the adhesive layer of the present invention, an adhesive layer including the adhesive layer of the present invention and other adhesive layers (adhesive layers other than the adhesive layer of the present invention), and the like. The pressure-sensitive adhesive layer with a base material includes: an adhesive layer having the adhesive layer of the present invention on both sides of a substrate, an adhesive layer having the adhesive layer of the present invention on one side of a substrate and having another adhesive layer on the other side, and the like. As the "substrate (substrate layer)" constituting the "adhesive layer with substrate", the same plastic film as the substrate of the present invention can be used.

The recovery rate of the adhesive layer of the present invention was 95% or less as determined in the shear test described below.

< shear test >)

Recovery (%) = (strain amount a-strain amount B)/strain amount a×100

The above "shear test" is described with reference to the drawings. Fig. 5 is a schematic diagram for explaining a shear test, 40 denotes an adhesive layer, and 41 and 42 denote parallel plates.

The adhesive layer 40 is a disc-shaped adhesive layer having a thickness of 2mm and a diameter of 7.9mm, and is constituted by the adhesive layer of the present invention, and the parallel plates 41 and 42 each have an upper surface and a bottom surface having a diameter of 7.9mm, and are constituted by, for example, stainless steel or the like (fig. 5 (a)). The upper surface of the parallel plate 41 and the bottom surface of the parallel plate 42 are aligned with and in contact with the bottom surface and the upper surface of the adhesive layer 40, respectively (fig. 5 (b)). Next, the peripheral temperature was set to 60 ℃, and a shearing force F600 seconds in the torsion direction of 500Pa was applied to the adhesive layer 40 (fig. 5 (c)). Then, the shearing force of the parallel plates 41 and 42 was released, and the mixture was left under a shearing force of 0Pa for 1800 seconds (FIG. 5 (d)). The "strain amount a" is a percentage (%) of the change in the twisting direction at the time (fig. 5 (c)) when the shear force F600 seconds is applied to the outer periphery (100%) of the adhesive layer 40 at the beginning (fig. 5 (b)). The "strain amount B" is a percentage (%) of the change in the twisting direction with respect to the outer periphery (100%) of the adhesive layer 40 at the initial (fig. 5 (B)) and at the time (fig. 5 (d)) of 1800 seconds after the shear force F600 seconds was applied and under the shear force 0 Pa. The recovery (%) was calculated from the following formula.

Recovery (%) = (strain amount a-strain amount B)/strain amount a×100

The structure in which the recovery rate of the adhesive layer of the present invention is 95% or less is preferable from the viewpoint that the adhesive layer can sufficiently follow shrinkage or expansion of the image display device of the present invention in the use environment, and can suppress swelling or peeling, and from the viewpoint that the transparency can be kept unchanged. In addition, in the case where there is a level difference in the uneven shape due to wiring or the like on an adherend such as an image display panel, the adhesive layer sufficiently follows the level difference, and the adhesive layer of the present invention is preferably configured to have a recovery rate of 95% or less from the viewpoint of being able to be filled without leaving bubbles or the like. The recovery rate of the pressure-sensitive adhesive layer of the present invention is preferably 94% or less, or 93.5% or less, from the viewpoint of suppressing swelling or peeling of the pressure-sensitive adhesive tape for optical use of the present invention, maintaining the transparency unchanged, and being able to follow the level difference. The lower limit of the recovery rate of the pressure-sensitive adhesive layer of the present invention is not particularly limited, and is preferably 70% or more, but may be 80% or more or 85% or more, from the viewpoint of workability such as difficulty in causing the pressure-sensitive adhesive layer to protrude from the end portion when the optical pressure-sensitive adhesive tape of the present invention is stored.

The strain amount a of the adhesive layer of the present invention is not particularly limited, but is preferably 3% or more. The configuration in which the strain amount a of the adhesive layer of the present invention is 3% or more is preferable from the viewpoint that the adhesive layer can sufficiently follow shrinkage or expansion of the image display device of the present invention in the use environment and can suppress swelling or peeling. In addition, in the case where there is a level difference in the uneven shape due to wiring or the like on an adherend such as an image display panel, the configuration in which the strain amount a of the adhesive layer of the present invention is 3% or more is also preferable from the viewpoint that the adhesive layer sufficiently follows the level difference and can be filled without leaving bubbles or the like. The strain amount a of the pressure-sensitive adhesive layer of the present invention is preferably 4% or more, or may be 5% or more, from the viewpoint of suppressing swelling or peeling of the pressure-sensitive adhesive tape for optical use of the present invention and being able to follow a height difference. The upper limit of the strain amount a of the present invention is not particularly limited, and is preferably 25% or less, or may be 20% or less or 15% or less, from the viewpoint of preventing the occurrence of defects such as protrusion of the adhesive layer from the end portion when the optical adhesive tape of the present invention is stored, and from the viewpoint of maintaining the transparency unchanged.

The strain amount B of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 0.1% or more. The configuration in which the strain amount B of the adhesive layer of the present invention is 0.1% or more is preferable from the viewpoint that the adhesive layer sufficiently follows shrinkage or expansion of the image display device of the present invention in the use environment and can suppress swelling or peeling. In addition, in the case where there is a level difference in the uneven shape due to wiring or the like on an adherend such as an image display panel, the configuration in which the strain amount B of the adhesive layer of the present invention is 0.1% or more is also preferable from the viewpoint that the adhesive layer sufficiently follows the level difference and can be filled without leaving bubbles or the like. The strain amount B of the pressure-sensitive adhesive layer of the present invention is preferably 0.2% or more, or may be 0.3% or more, from the viewpoint of suppressing swelling or peeling of the pressure-sensitive adhesive tape for optical use of the present invention and being able to follow a level difference. The upper limit of the strain amount B of the present invention is not particularly limited, and is preferably 10% or less, but may be 8% or less or 5% or less, from the viewpoint of preventing the occurrence of defects such as protrusion of the adhesive layer from the end portion when the optical adhesive tape of the present invention is stored, and from the viewpoint of maintaining the transparency unchanged.

The strain a, strain B, and recovery rate of the adhesive layer of the present invention were measured by shear test in examples described later. The strain amount a, strain amount B, recovery rate of the present invention can be adjusted by the composition (for example, the kind or molecular weight of the base polymer, the amount used, the monomer composition, the kind and amount of the functional group, the kind and amount of the crosslinking agent), the curing conditions (heating conditions, radiation irradiation conditions), and the like of the adhesive composition used to form the adhesive layer of the present invention.

The glass transition temperature (Tg) of the adhesive layer of the present invention is preferably-10℃or lower. The structure in which the adhesive layer of the present invention has a Tg of-10 ℃ or lower is preferable from the viewpoints that the stress relaxation property of the adhesive layer is maintained even in a low-temperature environment, the adhesive layer sufficiently follows shrinkage or expansion of the image display device of the present invention in a use environment, swelling or peeling can be suppressed, and adhesion to an adherend can be sufficiently ensured. The glass transition temperature of the pressure-sensitive adhesive layer of the present invention is preferably-15 ℃ or lower, or may be-20 ℃ or lower, from the viewpoint of suppressing swelling or peeling in the image display device of the present invention and good adhesion to an adherend. The lower limit of Tg of the pressure-sensitive adhesive layer of the present invention is not particularly limited, and is preferably-50 ℃ or higher, but may be-40 ℃ or higher, from the viewpoint of workability such as difficulty in causing the pressure-sensitive adhesive layer to protrude from the end portion when the optical pressure-sensitive adhesive tape of the present invention is stored.

The glass transition temperature (Tg) of the adhesive layer of the present invention was measured by dynamic viscoelasticity measurement in examples described later. The glass transition temperature (Tg) of the adhesive layer of the present invention can be adjusted by the composition (for example, the kind or molecular weight of the base polymer, the amount used, the monomer composition, the kind and amount of the functional group, the kind and amount of the crosslinking agent), the curing conditions (heating conditions, radiation irradiation conditions), and the like of the adhesive composition used to form the adhesive layer of the present invention.

The storage modulus at 70℃and 1Hz of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 80kPa or less. The pressure-sensitive adhesive layer of the present invention is preferably formed so that the pressure-sensitive adhesive layer can sufficiently follow shrinkage or expansion of the image display device of the present invention in the use environment and can suppress swelling or peeling, and has a storage modulus at 70 ℃ and 1Hz of 80kPa or less. In addition, in the case where there is a level difference in the uneven shape due to wiring or the like on an adherend such as an image display panel, the structure in which the adhesive layer sufficiently follows the level difference and can be filled without leaving bubbles or the like is also preferable in that the adhesive layer of the present invention has a storage modulus at 70 ℃ and 1Hz of 80kPa or less. The storage modulus at 70℃and 1Hz of the pressure-sensitive adhesive layer of the present invention is more preferably 70kPa or less, but may be 60kPa or less or 50kPa or less, from the viewpoint of suppressing the bulge or peeling of the pressure-sensitive adhesive tape for optical use of the present invention and enabling the pressure-sensitive adhesive tape to follow a height difference. The lower limit of the storage modulus at 70℃and 1Hz of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 1kPa or more, or may be 5kPa or more, from the viewpoint of workability such as difficulty in causing the pressure-sensitive adhesive layer to protrude from the end portion when the pressure-sensitive adhesive tape for optical use of the present invention is stored.

The loss tangent of the pressure-sensitive adhesive layer of the present invention at 70℃and 1Hz is not particularly limited, but is preferably 0.15 or more. The adhesive layer of the present invention is preferably formed so as to have a loss tangent of 0.15 or more at 70 ℃ and 1Hz, from the viewpoint of being able to sufficiently follow shrinkage or expansion of the image display device of the present invention in the use environment and to suppress swelling or peeling. In addition, in the case where there is a level difference in the uneven shape due to wiring or the like on an adherend such as an image display panel, the adhesive layer sufficiently follows the level difference, and the adhesive layer of the present invention is preferably configured so that it can be filled without leaving bubbles or the like, and the loss tangent at 70 ℃ and 1Hz is preferably 0.15 or more. The loss tangent at 70℃and 1Hz of the pressure-sensitive adhesive layer of the present invention is preferably 0.2 or more, but may be 0.25 or more or 0.3 or more, from the viewpoint of suppressing swelling or peeling of the pressure-sensitive adhesive tape for optical use of the present invention and enabling the pressure-sensitive adhesive tape to follow a level difference. The upper limit value of the loss tangent at 70℃and 1Hz of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 1 or less, or may be 0.8 or less, from the viewpoint of workability such as difficulty in causing the pressure-sensitive adhesive layer to protrude from the end portion when the optical pressure-sensitive adhesive tape of the present invention is stored.

The storage modulus at 70℃and 1Hz of the adhesive layer of the present invention was measured by dynamic viscoelasticity measurement in examples described later. The storage modulus and loss tangent at 70℃and 1Hz of the adhesive layer of the present invention can be adjusted by the composition (for example, the kind or molecular weight of the base polymer, the amount used, the monomer composition, the kind and amount of the functional group, the kind and amount of the crosslinking agent), the curing condition (heating condition, radiation irradiation condition) and the like of the adhesive composition used for forming the adhesive layer of the present invention.

For 1cm of the adhesive layer in the present invention ² The shear force when the adhesive area is adhered to the resin sheet and pulled at 23℃in the shear direction at a pulling speed of 0.06 mm/min is not particularly limited, and is preferably 20N/cm ² The following is given. In the present specification, when referring to "shearing force", unless otherwise indicated, means "when 1cm of the adhesive layer is to be laminated ² The adhesive area was attached to the resin plate and was pulled at 23℃in the shear direction at a pulling speed of 0.06 mm/min.

The pressure-sensitive adhesive layer of the present invention has a shear force of 20N/cm from the viewpoint that the pressure-sensitive adhesive layer of the present invention can sufficiently follow shrinkage or expansion of the image display device of the present invention in the use environment and can suppress swelling or peeling ² The following configuration is preferable. In addition, in the case where there is a level difference in the uneven shape due to wiring or the like on an adherend such as an image display panel, the pressure-sensitive adhesive layer sufficiently follows the level difference, and can be filled without leaving bubbles or the like, and the pressure-sensitive adhesive layer of the present invention has a shear force of 20N/cm ² The following configuration is also preferable. The shear force of the pressure-sensitive adhesive layer of the present invention is more preferably 15N/cm from the viewpoint of suppressing bulge or peeling of the pressure-sensitive adhesive tape for optical use of the present invention and being able to follow the height difference ² Hereinafter, 13N/cm may be used ² The following is given. The lower limit of the shearing force of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 5N/cm from the viewpoint of workability such as difficulty in causing the pressure-sensitive adhesive layer to protrude from the end portion when the optical pressure-sensitive adhesive tape of the present invention is stored ² Above, 7N/cm may also be used ² The above.

The shear force of the adhesive layer of the present invention was measured by shear force measurement in examples described later. The shear force of the adhesive layer of the present invention can be adjusted by the composition (for example, the kind or molecular weight of the base polymer, the amount used, the monomer composition, the kind and amount of the functional group, the kind and amount of the crosslinking agent), the curing conditions (heating conditions, radiation irradiation conditions), and the like of the adhesive composition used to form the adhesive layer of the present invention.

The 300% tensile residual stress value of the adhesive layer of the present invention is not particularly limited, and is preferably 10N/cm ² The following is given. The adhesive layer of the present invention has a 300% tensile residual stress value of 10N/cm from the viewpoint that the adhesive layer of the present invention can sufficiently follow shrinkage or expansion of the image display device of the present invention in the use environment and can suppress swelling or peeling ² The following configuration is preferable. In addition, in the case where there is a level difference in the uneven shape due to wiring or the like on an adherend such as an image display panel, the adhesive layer sufficiently follows the level difference, and can be filled without leaving bubbles or the like, the 300% tensile residual stress value of the adhesive layer of the present invention is 10N/cm ² The following configuration is also preferable. From the viewpoint of suppressing the bulge or peeling of the optical adhesive tape of the present invention and being able to follow the height difference, the 300% tensile residual stress value of the adhesive layer of the present invention is more preferably 7N/cm ² Hereinafter, the concentration may be 5N/cm ² The following is given. The lower limit of the 300% tensile residual stress value of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 1N/cm from the viewpoint of workability such as difficulty in occurrence of a problem that the pressure-sensitive adhesive layer protrudes from the end portion when the pressure-sensitive adhesive tape for optical use of the present invention is stored ² Above, 1.5N/cm may be used ² The above.

The 300% tensile residual stress value of the adhesive layer of the present invention was measured by measuring the 300% tensile residual stress value in examples described later. The 300% tensile residual stress value of the adhesive layer of the present invention can be adjusted by the composition (for example, the kind or molecular weight of the base polymer, the amount used, the monomer composition, the kind and amount of the functional group, the kind and amount of the crosslinking agent), the curing conditions (heating conditions, radiation irradiation conditions), and the like of the adhesive composition used to form the adhesive layer of the present invention.

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer of the present invention is not particularly limited, and examples thereof include: acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine-containing adhesives, epoxy adhesives, and the like. Among them, an acrylic adhesive is preferable as an adhesive constituting the adhesive layer from the viewpoints of transparency, adhesiveness, weather resistance, cost, and ease of designing the adhesive. That is, the adhesive layer of the present invention is preferably an acrylic adhesive layer composed of an acrylic adhesive. The above-mentioned binders can be used singly or in combination of two or more.

The acrylic pressure-sensitive adhesive layer contains an acrylic polymer as a base polymer. The acrylic polymer is a polymer containing an acrylic monomer (a monomer having a (meth) acryloyl group in a molecule) as a monomer component constituting the polymer. The acrylic polymer is preferably a polymer containing an alkyl (meth) acrylate as a monomer component constituting the polymer. The acrylic polymer may be used alone or in combination of two or more.

The adhesive composition forming the adhesive layer of the present invention may be in any form. For example, the adhesive composition may be of emulsion type, solvent type (solution type), active energy ray-curable type, hot melt type (hot melt type), or the like. Among them, solvent-based and active energy ray-curable adhesive compositions are preferred from the viewpoint of productivity and easiness in obtaining an adhesive layer excellent in optical characteristics and appearance. In particular, the active energy ray-curable adhesive composition is preferable in that the various characteristics of the adhesive layer (in particular, strain amount a, strain amount B, recovery rate, glass transition temperature, etc.) can be easily controlled within a predetermined range.

That is, the adhesive layer of the present invention is preferably an acrylic adhesive layer containing an acrylic polymer as a base polymer, and is formed of an active energy ray-curable acrylic adhesive composition.

Examples of the active energy ray include: ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, electron rays and the like; ultraviolet rays and the like, and ultraviolet rays are particularly preferable. That is, the active energy ray-curable adhesive composition is preferably an ultraviolet ray-curable adhesive composition.

As the pressure-sensitive adhesive composition (acrylic pressure-sensitive adhesive composition) for forming the acrylic pressure-sensitive adhesive layer, for example, there can be mentioned: an acrylic adhesive composition comprising an acrylic polymer as an essential component; or an acrylic pressure-sensitive adhesive composition comprising a mixture of monomers (monomers) constituting the acrylic polymer (sometimes referred to as "monomer mixture") or a part of the polymer thereof as an essential component. The former may be, for example, a so-called solvent-type acrylic pressure-sensitive adhesive composition. The latter may be, for example, a so-called active energy ray-curable acrylic pressure-sensitive adhesive composition. The "monomer mixture" mentioned above means a mixture containing monomer components constituting a polymer. The term "partial polymer" is sometimes referred to as "prepolymer" and refers to a composition in which one or more of the monomer components in the monomer mixture are partially polymerized.

The acrylic polymer is a polymer formed (formed) from an acrylic monomer as a necessary monomer component (monomer component). The acrylic polymer is preferably a polymer formed by (or including) an alkyl (meth) acrylate as an essential monomer component. That is, the acrylic polymer preferably contains an alkyl (meth) acrylate as a structural unit. In the present specification, "(meth) acrylic" means "acrylic" and/or "methacrylic" ("acrylic" and "methacrylic" either or both), and others are the same. The acrylic polymer is composed of one or two or more monomer components.

The alkyl (meth) acrylate as the essential monomer component is preferably an alkyl (meth) acrylate having a linear or branched alkyl group. The alkyl (meth) acrylate may be used alone or in combination of two or more.

The alkyl (meth) acrylate having a linear or branched alkyl group is not particularly limited, and examples thereof include: methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, stearyl ((meth) acrylate), isostearyl (meth) acrylate, nonadecyl (meth) acrylate, and the like are linear or branched (meth) acrylic acid having from 1 to 20 carbon atoms, the alkyl (meth) acrylate having a linear or branched alkyl group is preferably an alkyl (meth) acrylate having a linear or branched alkyl group having 4 to 18 carbon atoms, more preferably 2-ethylhexyl acrylate (2 EHA), isostearyl acrylate (ISTA), lauryl Acrylate (LA) or Butyl Acrylate (BA). The alkyl (meth) acrylate having a linear or branched alkyl group may be used singly or in combination of two or more.

The ratio of the alkyl (meth) acrylate is not particularly limited, but is preferably 50% by weight or more (for example, 50% by weight to 100% by weight), more preferably 53% by weight to 90% by weight, and still more preferably 55% by weight to 85% by weight, of the total monomer components (100% by weight) constituting the acrylic polymer.

The acrylic pressure-sensitive adhesive composition may contain the above alkyl (meth) acrylate in addition to the above acrylic polymer. When the acrylic pressure-sensitive adhesive composition contains an alkyl (meth) acrylate in addition to the acrylic polymer, the content (amount) of the alkyl (meth) acrylate is preferably 10 parts by weight or more (for example, 10 parts by weight to 100 parts by weight), more preferably 20 parts by weight to 90 parts by weight, still more preferably 30 parts by weight to 80 parts by weight, relative to 100 parts by weight of the acrylic polymer.

The acrylic polymer may contain the above alkyl (meth) acrylate and a copolymerizable monomer as a monomer component constituting the polymer. That is, the acrylic polymer may contain a copolymerizable monomer as a structural unit. The copolymerizable monomer may be used alone or in combination of two or more.

The copolymerizable monomer is not particularly limited, and preferable examples thereof include from the viewpoint of easily controlling the above-mentioned various characteristics of the pressure-sensitive adhesive layer (in particular, strain amount a, strain amount B, recovery rate, glass transition temperature, etc.) within a predetermined range, from the viewpoint of suppressing white turbidity in a high-humidity environment and improving durability, adhesion reliability, compatibility with various additives such as ultraviolet absorbers, and transparency: a monomer having a nitrogen atom in the molecule, a monomer having a hydroxyl group in the molecule. That is, the acrylic polymer preferably contains a monomer having a nitrogen atom in the molecule as a structural unit. The acrylic polymer preferably contains a monomer having a hydroxyl group in the molecule as a structural unit.

The monomer having a nitrogen atom in a molecule is a monomer (monomer) having at least one nitrogen atom in a molecule (in one molecule). In the present specification, the "monomer having a nitrogen atom in a molecule" described above may be referred to as "monomer containing a nitrogen atom". The nitrogen atom-containing monomer is not particularly limited, and preferable examples include: cyclic nitrogen-containing monomers, (meth) acrylamides, and the like. The nitrogen atom-containing monomer may be used alone or in combination of two or more.

The cyclic nitrogen-containing monomer is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and has a cyclic nitrogen structure. The cyclic nitrogen structure preferably has a nitrogen atom in the cyclic structure.

Examples of the cyclic nitrogen-containing monomer include: n-vinyl cyclic amide (lactam-based vinyl monomer), vinyl monomer having nitrogen-containing heterocycle, and the like.

Examples of the N-vinyl cyclic amide include N-vinyl cyclic amides represented by the following formula (1).

(in the formula (1), R ¹ Represents a divalent organic group

R in the above formula (1) ¹ The divalent organic group is preferably a divalent saturated hydrocarbon group or an unsaturated hydrocarbon group, and more preferably a divalent saturated hydrocarbon group (for example, an alkylene group having 3 to 5 carbon atoms or the like).

Examples of the N-vinyl cyclic amide represented by the above formula (1) include: n-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1, 3-oxazin-2-one, N-vinyl-3, 5-morpholindione, and the like.

Examples of the vinyl monomer having a nitrogen-containing heterocycle include: and acrylic monomers having nitrogen-containing heterocyclic rings such as morpholine ring, piperidine ring, pyrrolidine ring, piperazine ring, and the like.

The vinyl monomer having a nitrogen-containing heterocycle is not particularly limited, and examples thereof include: (meth) acryloylmorpholine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinylpyrzine, N-vinylmorpholine, N-vinylpyrazole, vinylpyridine, vinyloxazole, vinylisoxazole, vinylthiazole, vinylisothiazole, vinylpyridazine, (meth) acryloylpyrrolidone, (meth) acryloylpyrrolidine, (meth) acryloylpiperidine, and the like.

Among the above vinyl monomers having a nitrogen-containing heterocycle, the acrylic monomer having a nitrogen-containing heterocycle is preferable, and (meth) acryloylmorpholine, (meth) acryloylpyrrolidine and (meth) acryloylpiperidine are more preferable.

Examples of the (meth) acrylamides include: (meth) acrylamide, N-alkyl (meth) acrylamide, N-dialkyl (meth) acrylamide, and the like. Examples of the N-alkyl (meth) acrylamide include: n-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-N-butyl (meth) acrylamide, N-octyl (meth) acrylamide, and the like. The N-alkyl (meth) acrylamide includes (meth) acrylamides having an amino group such as dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, and dimethylaminopropyl (meth) acrylamide. Examples of the N, N-dialkyl (meth) acrylamide include: n, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-dipropyl (meth) acrylamide, N-diisopropyl (meth) acrylamide, N-di-N-butyl (meth) acrylamide, N-di-t-butyl (meth) acrylamide, and the like.

The (meth) acrylamides include, for example, various N-hydroxyalkyl (meth) acrylamides. Examples of the N-hydroxyalkyl (meth) acrylamide include: n-methylol (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, N- (1-hydroxypropyl) (meth) acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, N- (4-hydroxybutyl) (meth) acrylamide, N-methyl-N- (2-hydroxyethyl) (meth) acrylamide, and the like.

The (meth) acrylamides include, for example, various N-alkoxyalkyl (meth) acrylamides. Examples of the N-alkoxyalkyl (meth) acrylamide include: n-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, and the like.

Examples of the nitrogen atom-containing monomer other than the cyclic nitrogen-containing monomer and the (meth) acrylamide include: amino group-containing monomers, cyano group-containing monomers, imide group-containing monomers, isocyanate group-containing monomers, and the like. Examples of the amino group-containing monomer include: aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, and the like. Examples of the cyano group-containing monomer include: acrylonitrile, methacrylonitrile, and the like. Examples of the imide group-containing monomer include: maleimide monomers (e.g., N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.), itaconimide monomers (e.g., N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N- (2-ethylhexyl) itaconimide, N-laurel Gui Jiyi itaconimide, N-cyclohexylitaconimide, etc.), succinimide monomers (e.g., N- (meth) acryloyloxymethylenesuccinimide, N- (meth) acryl-6-oxyhexamethylenesuccinimide, N- (meth) acryl-8-oxyoctamethylenesuccinimide, etc.), and the like. Examples of the isocyanate group-containing monomer include: 2- (meth) acryloyloxyethyl isocyanate, and the like.

Among them, the above-mentioned nitrogen atom-containing monomer is preferably a cyclic nitrogen-containing monomer, and more preferably an N-vinyl cyclic amide. More specifically, N-vinyl-2-pyrrolidone (NVP) is particularly preferable.

In the case where the acrylic polymer contains the monomer containing a nitrogen atom as a monomer component constituting the polymer, the ratio of the monomer containing a nitrogen atom in the total monomer components (100 wt%) constituting the acrylic polymer is not particularly limited, but is preferably 1 wt% or more, more preferably 3 wt% or more, and still more preferably 5 wt% or more. When the ratio of the nitrogen atom-containing monomer is 1% by weight or more, the suppression of white turbidity and the durability in a high humidity environment are further improved, and high adhesion reliability can be obtained, which is preferable. The upper limit of the ratio of the nitrogen atom-containing monomer is preferably 30% by weight or less, more preferably 25% by weight or less, and even more preferably 20% by weight or less, from the viewpoints of obtaining an adhesive layer having moderate flexibility, obtaining an adhesive layer excellent in transparency, and easily controlling the various characteristics of the adhesive layer (in particular, strain amount a, strain amount B, recovery rate, glass transition temperature, etc.) within a predetermined range.

The monomer having a hydroxyl group in a molecule is a monomer having at least one hydroxyl group (hydroxyl group) in a molecule (one molecule), and examples thereof include a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a hydroxyl group. Wherein the monomer having a hydroxyl group in the molecule does not include the monomer having a nitrogen atom. That is, in the present specification, a monomer having both a nitrogen atom and a hydroxyl group in the molecule is contained in the "monomer containing a nitrogen atom". In the present specification, the "monomer having a hydroxyl group in a molecule" described above is sometimes referred to as "monomer containing a hydroxyl group". The hydroxyl group-containing monomer may be used singly or in combination of two or more.

Examples of the hydroxyl group-containing monomer include: hydroxy group-containing (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate, hydroxydecyl (meth) acrylate, hydroxylauryl (meth) acrylate, and (4-hydroxymethylcyclohexyl) acrylate; vinyl alcohol; allyl alcohol, and the like.

Among them, the hydroxyl group-containing monomer is preferably a hydroxyl group-containing (meth) acrylate, and more preferably 2-hydroxyethyl acrylate (HEA) or 4-hydroxybutyl acrylate (4 HBA).

In the case where the acrylic polymer contains the hydroxyl group-containing monomer as the monomer component constituting the polymer, the ratio of the hydroxyl group-containing monomer in the total monomer components (100 wt%) constituting the acrylic polymer is not particularly limited, but from the viewpoints of suppressing white turbidity in a high-humidity environment, improving durability, and obtaining high adhesive reliability, the ratio of the hydroxyl group-containing monomer is preferably 0.5 wt% or more, more preferably 0.8 wt% or more, and even more preferably 1 wt% or more. In addition, from the viewpoint of easy control of the various properties of the pressure-sensitive adhesive layer (in particular, strain amount a, strain amount B, recovery rate, glass transition temperature, etc.) within a predetermined range, the upper limit of the ratio of the hydroxyl group-containing monomer is preferably 30% by weight or less, more preferably 25% by weight or less, and still more preferably 20% by weight or less.

In addition, the acrylic pressure-sensitive adhesive composition may contain a hydroxyl group-containing monomer in addition to the acrylic polymer, for the purpose of further enhancing the above-described effect by the hydroxyl group-containing monomer. When the acrylic pressure-sensitive adhesive composition contains a hydroxyl group-containing monomer in addition to the acrylic polymer, the content (blending amount) of the hydroxyl group-containing monomer is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and still more preferably 5 parts by weight or more, relative to 100 parts by weight of the acrylic polymer. When the content of the hydroxyl group-containing monomer is 5 parts by weight or more, white turbidity in a high humidity environment and further improvement in durability are suppressed, and higher adhesion reliability can be obtained, which is preferable. The upper limit of the content (blending amount) of the hydroxyl group-containing monomer is preferably 30 parts by weight or less, more preferably 25 parts by weight or less, still more preferably 20 parts by weight or less, and particularly preferably 17 parts by weight or less, from the viewpoints of the cohesive force, the ease of obtaining tackiness and adhesion reliability, and the ease of controlling the various properties of the pressure-sensitive adhesive layer (in particular, strain amount a, strain amount B, recovery rate, glass transition temperature, etc.) within a predetermined range.

The total ratio of the nitrogen atom-containing monomer and the hydroxyl group-containing monomer in the total monomer components (100 wt%) constituting the acrylic polymer is not particularly limited, but is preferably 5 wt% or more, more preferably 10 wt% or more, and even more preferably 15 wt% or more, from the viewpoints of suppressing white turbidity in a high-humidity environment, improving durability, and obtaining high adhesive reliability. The upper limit of the total of the above-mentioned ratios is preferably 50% by weight or less, more preferably 40% by weight or less, and even more preferably 35% by weight or less, from the viewpoint of obtaining an adhesive layer having moderate flexibility, obtaining an adhesive layer excellent in transparency, and easily controlling the above-mentioned various characteristics of the adhesive layer (in particular, strain amount a, strain amount B, recovery rate, glass transition temperature, etc.) within a predetermined range.

Examples of copolymerizable monomers other than the nitrogen atom-containing monomer and the hydroxyl group-containing monomer include alicyclic structure-containing monomers. The alicyclic structure-containing monomer is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and has an alicyclic structure. For example, alkyl (meth) acrylate having a cycloalkyl group is contained in the above alicyclic structure-containing monomer. The alicyclic structure-containing monomer can be used singly or in combination of two or more.

The alicyclic structure in the alicyclic structure-containing monomer is a cyclic hydrocarbon structure, and the alicyclic structure preferably has 5 or more carbon atoms, more preferably has 6 to 24 carbon atoms, still more preferably has 6 to 15 carbon atoms, and particularly preferably has 6 to 10 carbon atoms.

Examples of the alicyclic structure-containing monomer include: a (meth) acrylic monomer such as cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, cyclooctyl (meth) acrylate, isobornyl (meth) acrylate, tetrahydrodicyclopentadiene (meth) acrylate, HPMPA represented by the following formula (2), TMA-2 represented by the following formula (3), HCPA represented by the following formula (4). In the following formula (4), the bonding site between the cyclohexyl ring and the structural formula in the brackets, which are connected by a wire, is not particularly limited. Among them, cyclohexyl (meth) acrylate and isobornyl (meth) acrylate are preferable.

In the case where the acrylic polymer contains the alicyclic structure-containing monomer as a monomer component constituting the polymer, the ratio of the alicyclic structure-containing monomer in the total monomer components (100 wt%) constituting the acrylic polymer is not particularly limited, and is preferably 10 wt% or more from the viewpoint of improving durability and obtaining high adhesive reliability. In addition, from the viewpoint of obtaining an adhesive layer having moderate flexibility, and from the viewpoint of easily controlling the above-mentioned various properties (in particular, strain amount a, strain amount B, recovery rate, glass transition temperature, etc.) of the adhesive layer within a predetermined range, the upper limit of the ratio of the alicyclic structure-containing monomer is preferably 50% by weight or less, more preferably 40% by weight or less, and still more preferably 30% by weight or less.

Further, examples of copolymerizable monomers include: a polyfunctional monomer. Examples of the polyfunctional monomer include: hexanediol di (meth) acrylate, butanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, and the like. The polyfunctional monomer may be used alone or in combination of two or more.

In the case where the acrylic polymer contains the polyfunctional monomer as the monomer component constituting the polymer, the ratio of the polyfunctional monomer in the total monomer components (100 wt%) constituting the acrylic polymer is not particularly limited, but is preferably 0.5 wt% or less (for example, 0 wt% or more and 0.2 wt% or less) from the viewpoint of easily controlling the various characteristics (in particular, strain amount a, strain amount B, recovery rate, glass transition temperature, etc.) of the pressure-sensitive adhesive layer within a predetermined range.

The polyfunctional monomer may be incorporated into the acrylic pressure-sensitive adhesive composition in addition to the acrylic polymer. When the acrylic pressure-sensitive adhesive composition contains a polyfunctional monomer in addition to the acrylic polymer, the content (blending amount) of the polyfunctional monomer is preferably 0.5 parts by weight or less (for example, 0 parts by weight or more and 0.5 parts by weight or less) and more preferably 0.2 parts by weight or less (for example, 0 parts by weight or more and 0.2 parts by weight or less) per 100 parts by weight of the acrylic polymer, from the viewpoint of easily controlling the above-mentioned various characteristics of the pressure-sensitive adhesive layer (in particular, strain amount a, strain amount B, recovery rate, glass transition temperature, etc.) within a predetermined range.

In addition, as the copolymerizable monomer, alkoxyalkyl (meth) acrylate is exemplified. The alkoxyalkyl (meth) acrylate is not particularly limited, and examples thereof include: 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 4-methoxybutyl (meth) acrylate, 4-ethoxybutyl (meth) acrylate, and the like. Among them, the above alkoxyalkyl (meth) acrylate is preferably an alkoxyalkyl acrylate, and more preferably 2-methoxyethyl acrylate (MEA). The alkoxyalkyl (meth) acrylate may be used alone or in combination of two or more.

In the case where the acrylic polymer contains the alkoxyalkyl (meth) acrylate as a monomer component constituting the polymer, the ratio of the alkyl (meth) acrylate to the alkoxyalkyl (meth) acrylate is not particularly limited, and the following is true: the latter ] (weight ratio), preferably greater than 100:0 and 25 or less: 75, more preferably greater than 100:0 and 50 or less: 50.

examples of the copolymerizable monomer include: carboxyl group-containing monomers, epoxy group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, aromatic hydrocarbon group-containing (meth) acrylates, vinyl esters, aromatic vinyl compounds, olefins or dienes, vinyl ethers, vinyl chloride, and the like. Examples of the carboxyl group-containing monomer include: examples of the carboxylic group-containing monomer include acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride. Examples of the epoxy group-containing monomer include: glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and the like. Examples of the sulfonic acid group-containing monomer include: sodium vinylsulfonate, and the like. Examples of the phosphate group-containing monomer include: 2-hydroxyethyl acryloyl phosphate, and the like. Examples of the (meth) acrylate having an aromatic hydrocarbon group include: phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, and the like. Examples of the vinyl esters include: vinyl acetate, vinyl propionate, and the like. Examples of the aromatic vinyl compound include: styrene, vinyl toluene, and the like. Examples of the olefins or diolefins include: ethylene, propylene, butadiene, isoprene, isobutylene, and the like. Examples of the vinyl ethers include: vinyl alkyl ethers, and the like.

From the viewpoint of obtaining an acrylic pressure-sensitive adhesive layer having excellent corrosion resistance, the acrylic polymer preferably contains no or substantially no acid group-containing monomer as a monomer component constituting the polymer, and particularly preferably contains no or substantially no carboxyl group-containing monomer. Examples of the acid group-containing monomer include: carboxyl group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, and the like. Specifically, the case where the ratio of the acid group-containing monomer in the total monomer components (100% by weight) constituting the acrylic polymer is 0.05% by weight or less (preferably 0.01% by weight or less) can be said to be a case where the acid group-containing monomer is substantially not contained.

The content of the base polymer (particularly, acrylic polymer) in the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 50% by weight or more (for example, 50% by weight to 100% by weight), more preferably 80% by weight or more (for example, 80% by weight to 100% by weight), and further preferably 90% by weight or more (for example, 90% by weight to 100% by weight) with respect to 100% by weight of the total weight of the pressure-sensitive adhesive layer of the present invention.

The weight average molecular weight (Mw) of the acrylic polymer is 100000 ～ 5000000, preferably 500000 ～ 4000000, and more preferably 750000 ～ 3000000. From the viewpoints of improving the adhesive force and the foaming peel resistance, a structure in which the weight average molecular weight of the acrylic polymer is 100000 or more is preferable. On the other hand, a structure in which the weight average molecular weight of the acrylic polymer is 5000000 or less is preferable from the viewpoints of easy improvement of adhesion and improvement of foaming peel resistance.

The weight average molecular weight (Mw) of the acrylic polymer can be obtained by GPC method and converted into polystyrene. For example, the measurement can be performed under the following conditions using a high-speed GPC apparatus "HPLC-8120GPC" manufactured by Tosoh Corp.

Column: TSKgel Super HZM-H/HZ4000/HZ3000/HZ2000

Solvent: tetrahydrofuran (THF)

Flow rate: 0.6 ml/min

The glass transition temperature (Tg) of the acrylic polymer is not particularly limited, but is preferably from-70℃to-10 ℃, more preferably from-65℃to-15 ℃, and even more preferably from-60℃to-20 ℃. When the glass transition temperature of the acrylic polymer is at least-70 ℃, the cohesive force is improved, and the foaming/peeling resistance is easily improved, which is preferable. In addition, a structure in which the glass transition temperature of the acrylic polymer is-10 ℃ or lower is preferable from the viewpoint that the stress relaxation property of the adhesive layer can be maintained even in a low-temperature environment, the adhesive layer sufficiently follows shrinkage or expansion of the image display device of the present invention in a use environment, swelling or peeling can be suppressed, and adhesion to an adherend can be sufficiently ensured.

The glass transition temperature (Tg) of the acrylic polymer is a glass transition temperature (theoretical value) expressed by the following FOX formula.

1/Tg＝W ₁ /Tg ₁ +W ₂ /Tg ₂ +……+W _n /Tg _n

In the above formula, tg means the glass transition temperature (unit: K) of the acrylic polymer, tg _i Represents the glass transition temperature (unit: K), W of monomer i when it forms a homopolymer _i The weight fraction of monomer i in the total monomer components (i=1, 2, … … n) is shown.

The following values can be used as Tg of the homopolymer of the monomer constituting the acrylic polymer.

2-ethylhexyl acrylate at-70 DEG C

N-hexyl acrylate at-65 deg.c

N-octyl acrylate at-65 deg.C

Isononyl acrylate at-60 DEG C

N-nonyl acrylate-58 DEG C

N-butyl acrylate at-55deg.C

Ethyl acrylate at-20 deg.c

Lauryl acrylate at 0 DEG C

2-ethylhexyl methacrylate-10 DEG C

Methyl acrylate at 8 DEG C

N-butyl methacrylate at 20 DEG C

Methyl methacrylate 105 DEG C

Acrylic acid 106 DEG C

Methacrylic acid 228 DEG C

Vinyl acetate 32 DEG C

Styrene at 100 DEG C

Further, as Tg of the homopolymer of the above-described monomer, the values described in "polymer handbook" (3 rd edition, john Wiley & Sons, inc., 1989) can be used. Further, as Tg of the homopolymer of the monomer which is not described in the above document, a value obtained by the above measurement method (peak top temperature of tan δ obtained by the viscoelasticity test) can be used.

The base polymer such as the acrylic polymer contained in the pressure-sensitive adhesive layer of the present invention is obtained by polymerizing a monomer component. The polymerization method is not particularly limited, and examples thereof include: solution polymerization, emulsion polymerization, bulk polymerization, polymerization by irradiation with active energy rays (active energy ray polymerization), and the like. Among them, the solution polymerization method and the active energy ray polymerization method are preferable from the viewpoints of transparency of the adhesive layer, cost and the like, and the active energy ray polymerization method is more preferable.

In addition, various general solvents can be used in the polymerization of the above monomer components. Examples of the solvent include: esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; organic solvents such as ketones including methyl ethyl ketone and methyl isobutyl ketone. The solvent may be used alone or in combination of two or more.

In the polymerization of the monomer component, a polymerization initiator such as a thermal polymerization initiator and a photopolymerization initiator (photoinitiator) may be used depending on the kind of polymerization reaction. The polymerization initiator may be used alone or in combination of two or more.

The thermal polymerization initiator is not particularly limited, and examples thereof include: azo-based polymerization initiators, peroxide-based polymerization initiators (e.g., dibenzoyl peroxide, t-butyl peroxymaleate, etc.), redox-type polymerization initiators, and the like. Among them, the azo-based polymerization initiator disclosed in Japanese patent application laid-open No. 2002-69411 is preferable. The azo-based polymerization initiator may be: 2,2 '-azobisisobutyronitrile (hereinafter sometimes referred to as "AIBN"), 2' -azobis (2-methylbutyronitrile) (hereinafter sometimes referred to as "AMBN"), dimethyl 2,2 '-azobis (2-methylpropionate), 4' -azobis (4-cyanovaleric acid), and the like. The thermal polymerization initiator may be used alone or in combination of two or more.

In the case where the azo-based polymerization initiator is used in the polymerization of the acrylic polymer, the amount of the azo-based polymerization initiator to be used is not particularly limited, and for example, the amount of the azo-based polymerization initiator to be used is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and further preferably 0.5 parts by weight or less, more preferably 0.3 parts by weight or less, based on 100 parts by weight of all the monomer components constituting the acrylic polymer.

The photopolymerization initiator is not particularly limited, and examples thereof include: benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, alpha-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photoactive oxime photopolymerization initiator, benzoin photopolymerization initiator, benzil photopolymerization initiator, benzophenone photopolymerization initiator, ketal photopolymerization initiator, thioxanthone photopolymerization initiator, and the like. Furthermore, it is also possible to list: acyl phosphine oxide photopolymerization initiator and titanocene photopolymerization initiator. Examples of the benzoin ether photopolymerization initiator include: benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-dimethoxy-1, 2-diphenylethane-1-one, anisoin methyl ether, and the like. As the above acetophenone photopolymerization initiator, for exampleThere may be mentioned: 2, 2-diethoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone, and the like. Examples of the α -ketol photopolymerization initiator include: 2-methyl-2-hydroxy-propiophenone and 1- [4- (2-hydroxyethyl) phenyl group ]-2-methylpropan-1-one and the like. Examples of the aromatic sulfonyl chloride photopolymerization initiator include: 2-naphthalenesulfonyl chloride, and the like. Examples of the photoactive oxime-type photopolymerization initiator include: 1-phenyl-1, 1-propanedione-2- (O-ethoxycarbonyl) oxime and the like. Examples of the benzoin photopolymerization initiator include: benzoin, and the like. Examples of the benzil photopolymerization initiator include: benzil, etc. Examples of the benzophenone photopolymerization initiator include: benzophenone, benzoyl benzoic acid, 3' -dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α -hydroxycyclohexyl phenyl ketone, and the like. Examples of the ketal photopolymerization initiator include: benzil dimethyl ketal, and the like. Examples of the thioxanthone photopolymerization initiator include: thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2, 4-dimethylthioxanthone, isopropylthioxanthone, 2, 4-diisopropylthioxanthone, dodecylthioxanthone, and the like. Examples of the acylphosphine oxide photopolymerization initiator include: 2,4, 6-trimethylbenzoyl diphenyl phosphine oxide, bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide, and the like. Examples of the titanocene-based photopolymerization initiator include: bis (eta) ⁵ -2, 4-cyclopentadien-1-yl) -bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) -titanium and the like. The photopolymerization initiator may be used alone or in combination of two or more.

In the case where the photopolymerization initiator is used in the polymerization of the acrylic polymer, the amount of the photopolymerization initiator to be used is not particularly limited, and is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, and further preferably 3 parts by weight or less, more preferably 1.5 parts by weight or less, based on 100 parts by weight of all monomer components constituting the acrylic polymer.

The acrylic pressure-sensitive adhesive composition preferably contains the acrylic polymer and an acrylic oligomer having a weight average molecular weight of 1000 to 30000. When the acrylic oligomer is contained, the adhesive property to an adherend at the interface of the optical adhesive tape of the present invention is improved, so that strong adhesive property is easily obtained, and further, excellent foaming peel resistance is easily obtained. In the present specification, the "acrylic oligomer having a weight average molecular weight of 1000 to 30000" may be simply referred to as "acrylic oligomer".

The acrylic oligomer is preferably an acrylic polymer comprising a (meth) acrylate having a cyclic structure in the molecule as an essential monomer component, and more preferably an acrylic polymer comprising a (meth) acrylate having a cyclic structure in the molecule and an alkyl (meth) acrylate having a linear or branched alkyl group as essential monomer components. That is, the acrylic oligomer is preferably an acrylic polymer containing a (meth) acrylate having a cyclic structure in the molecule as a monomer unit, and more preferably an acrylic polymer containing a (meth) acrylate having a cyclic structure in the molecule and an alkyl (meth) acrylate having a linear or branched alkyl group as a monomer unit.

The cyclic structure (ring) of the (meth) acrylate having a cyclic structure in a molecule (one molecule) (hereinafter, sometimes referred to as "ring-containing (meth) acrylate") may be any of an aromatic ring and a non-aromatic ring, and is not particularly limited. Examples of the aromatic ring include: an aromatic carbocycle [ for example, a monocyclic carbocycle such as a benzene ring, a condensed carbocycle such as a naphthalene ring, etc. ], various aromatic heterocyclic rings, etc. Examples of the non-aromatic ring include: non-aromatic aliphatic rings (non-aromatic alicyclic rings) [ for example, cycloalkane rings such as cyclopentane ring, cyclohexane ring, cycloheptane ring, cyclooctane ring, etc.; cycloolefin ring such as cyclohexene ring, etc.), a non-aromatic bridged ring [ for example, a bicyclic hydrocarbon ring in pinane, pinene, camphene, norbornane, norbornene, etc.; an aliphatic hydrocarbon ring having three or more rings (bridged hydrocarbon ring) among adamantane and the like ], a non-aromatic heterocycle [ for example, an epoxy ring, an oxolane ring, an oxetane ring and the like ], and the like.

Examples of the above-mentioned tricyclic or higher aliphatic hydrocarbon ring (tricyclic or higher bridged hydrocarbon ring) include: a tetrahydrodicyclopentadiene group represented by the following formula (5 a), a dihydrodicyclopentadiene group represented by the following formula (5 b), an adamantyl group represented by the following formula (5 c), a tetrahydrodicyclopentadiene group represented by the following formula (5 d), a dihydrodicyclopentadiene group represented by the following formula (5 e), and the like.

That is, examples of the (meth) acrylate containing a ring include: cycloalkyl (meth) acrylates such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, and cyclooctyl (meth) acrylate; (meth) acrylic esters having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth) acrylate; (meth) acrylic esters having an aliphatic hydrocarbon ring having three or more rings, such as tetrahydrodicyclopentadienyl (meth) acrylate, tetrahydrodicyclopentadienyloxyethyl (meth) acrylate, tetrahydrotricyclopentadienyl (meth) acrylate, 1-adamantyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, and 2-ethyl-2-adamantyl (meth) acrylate; aryl (meth) acrylates such as phenyl (meth) acrylate, aryloxyalkyl (meth) acrylate such as phenoxyethyl (meth) acrylate, arylalkyl (meth) acrylate such as benzyl (meth) acrylate, and (meth) acrylates having an aromatic ring. Among them, the (meth) acrylate containing a ring is particularly preferably a (meth) acrylate containing a non-aromatic ring, more preferably cyclohexyl acrylate (CHA), cyclohexyl methacrylate (CHMA), tetrahydrodicyclopentadiene acrylate (DCPA), tetrahydrodicyclopentadiene methacrylate (dcdma), and still more preferably tetrahydrodicyclopentadiene acrylate (DCPA) and tetrahydrodicyclopentadiene methacrylate (dcdma). The (meth) acrylate containing a ring may be used alone or in combination of two or more.

Among the above (meth) acrylates containing a non-aromatic ring, a (meth) acrylate having an aliphatic hydrocarbon ring having three or more rings (particularly, a bridged hydrocarbon ring having three or more rings) is particularly preferable from the viewpoint of less occurrence of polymerization inhibition. In addition, when a (meth) acrylate having a tetrahydrodicyclopentadiene group represented by the above formula (5 a), an adamantyl group represented by the above formula (5 c), or a tetrahydrodicyclopentadiene group represented by the above formula (5 d) is used, the foam peeling resistance can be further improved, and the adhesiveness to a low-polarity adherend such as polyethylene or polypropylene can be remarkably improved.

The content (ratio) of the above-mentioned ring-containing (meth) acrylate in all monomer units of the acrylic oligomer (total amount of monomer components constituting the acrylic oligomer) is not particularly limited, but is preferably 10 to 90 parts by weight, more preferably 20 to 80 parts by weight, relative to the total amount of monomer components constituting the acrylic oligomer (100 parts by weight). When the content of the cyclic (meth) acrylate is 10 parts by weight or more, the foaming peel resistance is easily improved, which is preferable. When the content of the cyclic (meth) acrylate is 90 parts by weight or less, the pressure-sensitive adhesive layer has appropriate flexibility, and is preferably easy to improve the adhesive force, the level difference absorbability, and the like.

Examples of the alkyl (meth) acrylate having a linear or branched alkyl group as the monomer unit of the acrylic oligomer include: methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, and the like are (meth) acrylates having 1 to 20 carbon atoms of alkyl groups. Among them, methyl Methacrylate (MMA) is preferable from the viewpoint of good compatibility with the acrylic polymer. The alkyl (meth) acrylate may be used alone or in combination of two or more.

The content (ratio) of the alkyl (meth) acrylate having a linear or branched alkyl group in all the monomer units (total amount of monomer components constituting the acrylic oligomer) of the acrylic oligomer is not particularly limited, but is preferably 10 to 90 parts by weight, more preferably 20 to 80 parts by weight, and even more preferably 20 to 60 parts by weight, relative to the total amount (100 parts by weight) of monomer components constituting the acrylic oligomer, from the viewpoint of foaming peel resistance. When the content of the alkyl (meth) acrylate having a linear or branched alkyl group is 10 parts by weight or more, it is particularly easy to improve the adhesion to an adherend made of an acrylic resin or a polycarbonate, and it is preferable.

The monomer unit of the acrylic oligomer may contain a monomer copolymerizable with these monomers (copolymerizable monomer) in addition to the above-mentioned (meth) acrylate containing a ring and the alkyl (meth) acrylate having a linear or branched alkyl group. The content (ratio) of the copolymerizable monomer in all the monomer units (total amount of monomer components constituting the acrylic oligomer) of the acrylic oligomer is not particularly limited, but is preferably 49.9 parts by weight or less (for example, 0 to 49.9 parts by weight), more preferably 30 parts by weight or less, based on the total amount (100 parts by weight) of monomer components constituting the acrylic oligomer. In addition, two or more copolymerizable monomers may be used singly or in combination.

The copolymerizable monomer (the copolymerizable monomer constituting the acrylic oligomer) as the monomer unit of the acrylic oligomer may be exemplified by: alkoxyalkyl (meth) acrylates [ e.g., 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 4-methoxybutyl (meth) acrylate, 4-ethoxybutyl (meth) acrylate, etc ]; hydroxy group-containing monomers [ e.g., hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, vinyl alcohol, allyl alcohol, etc. ]; amide group-containing monomers [ e.g., (meth) acrylamide, N-dimethyl (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, etc. ]; amino group-containing monomers [ e.g., aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, etc. ]; cyano group-containing monomers [ e.g., acrylonitrile, methacrylonitrile, etc. ]; sulfonic acid group-containing monomers [ e.g., sodium vinylsulfonate, etc. ]; a phosphoric acid group-containing monomer [ e.g., 2-hydroxyethyl acryl phosphate, etc. ]; an isocyanate group-containing monomer [ e.g., 2-methacryloxyethyl isocyanate, etc. ], an imide group-containing monomer [ e.g., cyclohexylmaleimide, isopropylmaleimide, etc. ], and the like.

As described above, the acrylic oligomer is preferably an acrylic polymer containing, as monomer units, a (meth) acrylate having a cyclic structure in the molecule and an alkyl (meth) acrylate having a linear or branched alkyl group. Among them, an acrylic polymer containing a cyclic (meth) acrylate and the above alkyl (meth) acrylate having a linear or branched alkyl group as monomer units is preferable. In the acrylic polymer containing the cyclic (meth) acrylate and the alkyl (meth) acrylate having a linear or branched alkyl group as monomer units, the amount of the cyclic (meth) acrylate relative to the total amount (100 parts by weight) of the monomer components constituting the acrylic oligomer is not particularly limited, and is preferably 10 to 90 parts by weight, more preferably 20 to 80 parts by weight. The content of the alkyl (meth) acrylate having a linear or branched alkyl group is not particularly limited, but is preferably 10 to 90 parts by weight, more preferably 20 to 80 parts by weight, and still more preferably 20 to 60 parts by weight.

Further, specific preferable configurations of the acrylic oligomer include: an acrylic polymer comprising (1) at least one monomer selected from the group consisting of tetrahydrodicyclopentadienyl acrylate, tetrahydrodicyclopentadienyl methacrylate, cyclohexyl acrylate and cyclohexyl methacrylate and (2) methyl methacrylate as a monomer unit. In the acrylic oligomer of the above-described particularly preferred specific constitution, the content of (1) tetrahydrodicyclopentadiene acrylate, tetrahydrodicyclopentadiene methacrylate, cyclohexyl acrylate and cyclohexyl methacrylate (in the case of containing two or more kinds, the total amount thereof) in all the monomer units of the acrylic oligomer is preferably 30 to 70 parts by weight and the content of (2) methyl methacrylate is preferably 30 to 70 parts by weight, relative to the total amount (100 parts by weight) of the monomer components constituting the acrylic oligomer. However, the acrylic oligomer is not limited to the specific configuration described above.

The acrylic oligomer can be obtained by polymerizing the above monomer components by a known or conventional polymerization method. Examples of the polymerization method of the acrylic oligomer include: solution polymerization, emulsion polymerization, bulk polymerization, polymerization by irradiation with active energy rays (active energy ray polymerization), and the like. Among them, bulk polymerization and solution polymerization are preferable, and solution polymerization is more preferable.

In the polymerization of the acrylic oligomer, various general solvents can be used. Examples of the solvent include: esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; organic solvents such as ketones including methyl ethyl ketone and methyl isobutyl ketone. It should be noted that two or more such solvents may be used singly or in combination.

In addition, in the polymerization of the acrylic oligomer, a known or conventional polymerization initiator (for example, a thermal polymerization initiator, a photopolymerization initiator, etc.) may be used. The polymerization initiator may be used alone or in combination of two or more.

Examples of the thermal polymerization initiator include: 2,2 '-Azobisisobutyronitrile (AIBN), 2' -azobis (2-methylbutyronitrile) (AMBN), dimethyl 2,2 '-azobis (2-methylpropionate), 4' -azobis (4-cyanovaleric acid) azo initiators such as 2,2 '-azobis (4-methoxy-2, 4-dimethylvaleronitrile), 2' -azobis (2, 4-dimethylvaleronitrile), 1 '-azobis (cyclohexane-1-carbonitrile), and 2,2' -azobis (2, 4-trimethylpentane); peroxide initiators such as benzoyl peroxide, t-butylhydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1-bis (t-butylperoxy) -3, 5-trimethylcyclohexane, and 1, 1-bis (t-butylperoxy) cyclododecane. In the case of performing solution polymerization, an oil-soluble polymerization initiator is preferably used. In addition, the thermal polymerization initiator may be used singly or in combination of two or more.

The amount of the thermal polymerization initiator used is not particularly limited, and is, for example, 0.1 to 15 parts by weight based on 100 parts by weight of all monomer units of the acrylic oligomer (the total amount of monomer components constituting the acrylic oligomer).

The photopolymerization initiator is not particularly limited, and examples thereof include the same photopolymerization initiators as those used in the polymerization of the acrylic polymer described above. The amount of the photopolymerization initiator to be used is not particularly limited and is appropriately selected.

In the polymerization of the acrylic oligomer, a chain transfer agent may be used for adjusting the molecular weight (specifically, for adjusting the weight average molecular weight to 1000 to 30000). Examples of the chain transfer agent include: 2-mercaptoethanol, α -thioglycerol, 2, 3-dimercapto-1-propanol, octylmercaptan, t-nonylthiol, dodecylmercaptan (lauryl mercaptan), t-dodecylmercaptan, glycidyl mercaptan, thioglycolic acid, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, ethylene glycol thioglycolate, neopentyl glycol thioglycolate, pentaerythritol thioglycolate, α -methylstyrene dimer, and the like. Among them, from the viewpoint of suppressing whitening of the optical adhesive tape of the present invention due to humidification, α -thioglycerol and methyl thioglycolate are preferable, and α -thioglycerol is particularly preferable. The chain transfer agent may be used alone or in combination of two or more.

The content (amount) of the chain transfer agent is not particularly limited, but is preferably 0.1 to 20 parts by weight, more preferably 0.2 to 15 parts by weight, and even more preferably 0.3 to 10 parts by weight, based on 100 parts by weight of the total monomer units of the acrylic oligomer (total amount of monomer components constituting the acrylic oligomer). By setting the content (amount) of the chain transfer agent within the above range, an acrylic oligomer having a weight average molecular weight of 1000 to 30000 can be easily obtained.

The weight average molecular weight (Mw) of the acrylic oligomer is 1000 to 30000, preferably 1000 to 20000, more preferably 1500 to 10000, still more preferably 2000 to 8000. Since the weight average molecular weight of the acrylic oligomer is 1000 or more, the adhesive force and retention characteristics are improved, and the foaming peel resistance is improved. On the other hand, since the weight average molecular weight of the acrylic oligomer is 30000 or less, the adhesive force is easily improved and the foaming peel resistance is improved.

The weight average molecular weight (Mw) of the acrylic oligomer can be obtained by GPC and converted into polystyrene. For example, the measurement can be performed under the following conditions using a high-speed GPC apparatus "HPLC-8120GPC" manufactured by Tosoh Corp.

Column: TSKgel Super HZM-H/HZ4000/HZ3000/HZ2000

Solvent: tetrahydrofuran (THF)

Flow rate: 0.6 ml/min

The glass transition temperature (Tg) of the acrylic oligomer is not particularly limited, but is preferably 20 to 300 ℃, more preferably 30 to 300 ℃, and even more preferably 40 to 300 ℃. When the glass transition temperature of the acrylic oligomer is 20℃or higher, the foaming peel resistance is easily improved, which is preferable. In addition, when the glass transition temperature of the acrylic oligomer is 300 ℃ or less, the adhesive layer has moderate flexibility, good adhesion, good level difference absorption, and excellent adhesion reliability are easily obtained, and thus is preferable.

The glass transition temperature (Tg) of the acrylic oligomer is a glass transition temperature (theoretical value) expressed by the FOX formula.

As Tg of the homopolymer of the monomer constituting the acrylic oligomer, the values described in table 1 below can be used. Further, as Tg of the homopolymer of the monomer not described in table 1, the values described in "polymer handbook" (3 rd edition, john Wiley & Sons, inc., 1989) can be used. Further, as Tg of the homopolymer of the monomer which is not described in the above document, a value obtained by the above measurement method (peak top temperature of tan δ obtained by the viscoelasticity test) can be used.

TABLE 1

The "DCPMA/MMA=60/40" copolymer in Table 1 means a copolymer of 60 parts by weight of DCPMA and 40 parts by weight of MMA.

The content of the acrylic oligomer in the case where the acrylic adhesive composition contains the acrylic polymer and the acrylic oligomer is not particularly limited, but the content of the acrylic oligomer is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, and even more preferably 2 to 10 parts by weight, relative to 100 parts by weight of the acrylic polymer. That is, the content of the acrylic oligomer in the adhesive composition is not particularly limited, but the content of the acrylic oligomer is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, and even more preferably 2 to 10 parts by weight, based on 100 parts by weight of the total monomer units of the acrylic polymer. The content of the acrylic oligomer in the acrylic pressure-sensitive adhesive composition is not particularly limited, and for example, the content of the acrylic oligomer is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, and even more preferably 2 to 10 parts by weight, relative to 100 parts by weight of the monomer mixture. When the content of the acrylic oligomer is 1 part by weight or more, excellent tackiness and excellent foaming peel resistance are easily obtained, which is preferable. In addition, when the content of the acrylic oligomer is 30 parts by weight or less, excellent transparency and adhesion reliability are easily obtained, which is preferable. In addition, from the viewpoint of easily controlling the above-mentioned various properties (in particular, strain amount a, strain amount B, recovery rate, glass transition temperature, etc.) of the pressure-sensitive adhesive layer within a predetermined range, the content of the acrylic oligomer is preferably 10 parts by weight or less, more preferably 8 parts by weight or less.

The method for producing the adhesive composition containing the acrylic polymer and the acrylic oligomer is not particularly limited. For example, the acrylic polymer is produced by adding an acrylic oligomer, an additive, or the like to a mixture of monomer components constituting the acrylic polymer or a partial polymer of a mixture of monomer components constituting the acrylic polymer (a monomer mixture forming the acrylic polymer or a partial polymer thereof) as necessary and mixing them.

The adhesive layer of the present invention is not particularly limited, and preferably contains an ultraviolet absorber (UVA). When the adhesive layer of the present invention contains an ultraviolet absorber, it is preferable from the viewpoint of being able to suppress damage of the image display panel caused by ultraviolet rays. The ultraviolet absorber may be used alone or in combination of two or more.

The ultraviolet absorber is not particularly limited, and examples thereof include: benzotriazole-based ultraviolet absorbers, hydroxyphenyl triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, hydroxybenzophenone-based ultraviolet absorbers, and the like.

Examples of the benzotriazole-based ultraviolet absorber (benzotriazole-based compound) include: 2- (2-hydroxy-5-t-butylphenyl) -2H-benzotriazole (trade name "TINUVIN PS", manufactured by BASF corporation), an ester compound of phenylpropionic acid with 3- (2H-benzotriazol-2-yl) -5- (1, 1-dimethylethyl) -4-hydroxy (C7-9 side chain and linear alkyl group) (trade name "TINUVIN 384-2", manufactured by BASF corporation), a mixture of octyl 3- [ 3-t-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl ] propionate and 2-ethylhexyl 3- [ 3-t-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl ] propionate (trade name "TINUVIN 109", BASF corporation), 2- (2H-benzotriazol-2-yl) -4, 6-bis (1-methyl-1-phenylethyl) phenol (trade name "TINUVIN 900", BASF corporation), 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1, 3-tetramethylbutyl) phenol (trade name "TINUVIN 928", BASF corporation), reaction product of methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate with polyethylene glycol 300 (trade name "TINUVIN 1130", manufactured by BASF corporation), 2- (2H-benzotriazol-2-yl) -P-cresol (trade name "TINUVIN P", manufactured by BASF corporation), 2- (2H-benzotriazol-2-yl) -4, 6-bis (1-methyl-1-phenylethyl) phenol (trade name "TINUVIN 234", manufactured by BASF corporation), 2- [ 5-chloro-2H-benzotriazol-2-yl ] -4-methyl-6-tert-butylphenol (trade name "TINUVIN 326", manufactured by BASF corporation), 2- (2H-benzotriazol-2-yl) -4, 6-di-tert-amylphenol (trade name "TINUVIN 328", manufactured by BASF corporation), 2- (2H-benzotriazol-2-yl) -4- (1, 3-tetramethylbutyl) phenol (trade name "TINUF", manufactured by BASF corporation), 2- [ 5-chloro-2H-benzotriazol-2-yl ] -4-methyl-6-tert-butylphenol (trade name "TINUVIN 326", manufactured by BASF corporation), 2- (2H-benzotriazol-2-yl) -4, 6-di-tert-amylphenol (trade name "TINUVIN 328", manufactured by BASF corporation), 2 (trade name "1N 2" 1H-3, 1, 3-tetramethylbutyl) phenol (2) and 2 methyl-4 (1) amine (1P), methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate reacted with polyethylene glycol 300 (trade name "TINUVIN 213", manufactured by BASF), 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol (trade name "TINUVIN 571", manufactured by BASF), 2- [ 2-hydroxy-3- (3, 4,5, 6-tetrahydrophthalimidomethyl) -5-methylphenyl ] benzotriazole (trade name "Sumisorb 250", manufactured by Sumitomo chemical Co., ltd.), 2' -methylenebis [6- (2H-benzotriazol-2-yl) -4-tert-octylphenol ] (trade name "ADK STAB LA-31", manufactured by ADEKA Co., ltd.) and the like.

Examples of the hydroxyphenyl triazine ultraviolet light absorber (hydroxyphenyl triazine compound) include: the reaction product of 2- (4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazin-2-yl) -5-hydroxyphenyl with [ (C10-C16 (mainly C12-C13) alkoxy) methyl ] oxirane (trade name "TINUVIN 400", manufactured by BASF corporation), 2- [4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazin-2-yl ] -5- [3- (dodecyloxy) -2-hydroxypropoxy ] phenol, the reaction product of 2- (2, 4-dihydroxyphenyl) -4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazine with glycidic acid (2-ethylhexyl) ester (trade name "TINUVIN 405", manufactured by BASF corporation), 2, 4-bis (2-hydroxy-4-butoxyphenyl) -6- (2, 4-dibutoxyphenyl) -1,3, 5-triazine (trade name "TINUVIN 460", manufactured by BASF corporation), 2- (4, 6-diphenyl-1, 3, 5-triazin-5-yloxy) -hexyloxy ] -phenol (trade name "1, 3, 5-triazin-5-yl) -2- (2-ethylhexyl) acrylate (trade name" TINUVIN 405", manufactured by BASF corporation), and (trade name" STAF-5-2, 5-bis (trade name "N-Butyl-5") ",6-hydroxy-4-2-butoxyphenyl",5-hydroxy-4-2-butoxyphenyl ",5-hydroxy",6-5-hydroxy ", ADEKA Co., ltd.), 2- (2-hydroxy-4- [ 1-octyloxycarbonylethoxy ] phenyl) -4, 6-bis (4-phenylphenyl) -1,3, 5-triazine (trade name "TINUVIN 479", manufactured by BASF corporation), and the like. Further, a compound represented by the following formula (6) (trade name "TINUVIN 477", manufactured by BASF corporation) may be cited.

Examples of the benzophenone-based ultraviolet absorber (benzophenone-based compound) and the hydroxybenzophenone-based ultraviolet absorber (hydroxybenzophenone-based compound) include: 2, 4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous salt and trihydrate), 2-hydroxy-4-octoxybenzophenone, 4-dodecoxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2' -dihydroxy-4-methoxybenzophenone (trade name "KEMISORB 111", manufactured by Chemipro chemical Co., ltd.), 2', 4' -tetrahydroxybenzophenone (trade name "SEESORB 106", manufactured by Shipro chemical Co., ltd.), 2' -dihydroxy-4, 4' -dimethoxybenzophenone, and the like.

Examples of the salicylate-based ultraviolet absorber (salicylate-based compound) include: phenyl 2-acryloyloxy benzoate, phenyl 2-acryloyloxy-3-methylbenzoate, phenyl 2-acryloyloxy-4-methylbenzoate, phenyl 2-acryloyloxy-5-methylbenzoate, phenyl 2-acryloyloxy-3-methoxybenzoate, phenyl 2-hydroxybenzoate, phenyl 2-hydroxy-3-methylbenzoate, phenyl 2-hydroxy-4-methylbenzoate, phenyl 2-hydroxy-5-methylbenzoate, phenyl 2-hydroxy-3-methoxybenzoate, 2, 4-di-t-butylphenyl 3, 5-di-t-butyl-4-hydroxybenzoate (trade name "TINUVIN 120", manufactured by BASF corporation), and the like.

Examples of the cyanoacrylate ultraviolet absorber (cyanoacrylate compound) include: alkyl 2-cyanoacrylates, cycloalkyl 2-cyanoacrylates, alkoxyalkyl 2-cyanoacrylates, alkenyl 2-cyanoacrylates, alkynyl 2-cyanoacrylates, and the like.

The ultraviolet absorber is preferably at least one ultraviolet absorber selected from the group consisting of benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers and hydroxyphenyl triazine ultraviolet absorbers, more preferably benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers, from the viewpoint of having high ultraviolet absorbability and further improving corrosion resistance (particularly UV resistance), from the viewpoint of easily obtaining an adhesive layer having excellent optical characteristics and high transparency, and from the viewpoint of having excellent light stability. Particularly preferred is a benzotriazole-based ultraviolet absorber wherein a phenyl group having a group having 6 or more carbon atoms and a hydroxyl group are bonded to a nitrogen atom constituting a benzotriazole ring as substituents.

Further, from the viewpoint of obtaining higher ultraviolet absorptivity and further improving corrosion resistance (particularly UV resistance), the above ultraviolet absorber preferably has an absorbance a obtained as described below of 0.5 or less.

Absorbance a: absorbance was measured by irradiating a 0.08% toluene solution of the ultraviolet absorber with light having a wavelength of 400 nm.

When the pressure-sensitive adhesive layer of the present invention contains an ultraviolet absorber, the content of the ultraviolet absorber in the pressure-sensitive adhesive layer (particularly, acrylic pressure-sensitive adhesive layer) of the present invention is not particularly limited, but from the viewpoint of further improving corrosion resistance (particularly, UV resistance), the content of the ultraviolet absorber is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, and even more preferably 0.1 parts by weight or more, relative to 100 parts by weight of the base polymer. In addition, from the viewpoint of suppressing occurrence of yellowing phenomenon of the adhesive accompanied by addition of the ultraviolet absorber, and obtaining excellent optical characteristics, high transparency, and excellent appearance characteristics, the upper limit of the content of the ultraviolet absorber is preferably 10 parts by weight or less, more preferably 9 parts by weight or less, and further preferably 8 parts by weight or less, relative to 100 parts by weight of the base polymer.

The adhesive layer of the present invention may contain a light stabilizer. When the adhesive layer of the present invention contains a light stabilizer, it is particularly preferable to contain the light stabilizer together with the ultraviolet absorber. The light stabilizer can capture radicals generated by photooxidation, and thus can improve the light resistance (particularly ultraviolet rays) of the adhesive layer. The light stabilizer may be used alone or in combination of two or more.

The light stabilizer is not particularly limited, and examples thereof include: phenolic light stabilizers (phenolic compounds), phosphorus-containing light stabilizers (phosphorus-containing compounds), thioether light stabilizers (thioether compounds), amine light stabilizers (amine compounds) (particularly hindered amine light stabilizers (hindered amine compounds)), and the like.

Examples of the phenolic light stabilizer (phenolic compound) include: 2, 6-di-tert-butyl-4-methylphenol, 4-hydroxymethyl-2, 6-di-tert-butylphenol, 2, 6-di-tert-butyl-4-ethylphenol, butylated hydroxyanisole, N-octadecyl 3- (4-hydroxy-3, 5-di-tert-butylphenyl) propionate, distearyl (4-hydroxy-3-methyl-5-tert-butyl) benzylmalonate, tocopherol, 2 '-methylenebis (4-methyl-6-tert-butylphenol), 2' -methylenebis (4-ethyl-6-tert-butylphenol), 4 '-methylenebis (2, 6-di-tert-butylphenol), 4' -butylidenebis (6-tert-butyl-m-cresol), 4 '-thiobis (6-tert-butyl-m-cresol), styrenated phenol, N, N' -hexamethylenebis (3, 5-di-tert-butyl-4-hydroxyhydrocinnamate), bis (ethyl 3, 5-di-tert-butyl-4-hydroxybenzylphosphonate) calcium, 1, 3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl ] methane, 1, 6-hexanediol bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], 2' -methylenebis (4-methyl-6-cyclohexylphenol), 2' -methylenebis [6- (1-methylcyclohexyl) -p-cresol ],1,3, 5-tris (4-tert-butyl-3-hydroxy-2, 6-dimethylbenzyl) isocyanurate, 1,3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, triethylene glycol bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate ], 2' -oxamidylbis [ ethyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], 6- (4-hydroxy-3, 5-di-tert-butylphenylamino) -2, 4-dioctylthio-1, 3, 5-triazine, bis [ 2-tert-butyl-4-methyl-6- (2-hydroxy-3-tert-butyl-5-methylbenzyl) phenyl ] terephthalate, 3,9- [ 3-di-tert-butyl-4-hydroxyphenyl ] -3, 5-oxo } -3- [3, 5-di-tert-butyl-4-hydroxyphenyl ] propane ] -2, 5-bis- [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] -, 6- (4-hydroxy-3, 5-di-tert-butylanilino) -2, 4-dioctyl-butyl-1, 5-triazine 3, 9-bis {2- [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyloxy ] -1, 1-dimethylethyl } -2,4,8, 10-tetraoxaspiro [5.5] undecane, etc.

Examples of the phosphorus-containing light stabilizer (phosphorus-containing compound) include: tris (nonylphenyl) phosphite, tris (2, 4-di-tert-butylphenyl) phosphite, tris [ 2-tert-butyl-4- (3-tert-butyl-4-hydroxy-5-methylphenylsulfanyl) -5-methylphenyl ] phosphite, tridecyl phosphite, octyl diphenyl phosphite, di (decyl) monophenyl phosphite, ditridecyl pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, di (nonylphenyl) pentaerythritol diphosphite, di (2, 4-di-tert-butylphenyl) pentaerythritol diphosphite pentaerythritol diphosphite bis (2, 6-di-tert-butyl-4-methylphenyl) ester, pentaerythritol diphosphite bis (2, 4, 6-tri-tert-butylphenyl) ester, isopropylidene diphenol diphosphite tetra (tridecyl) ester, 4' -n-butylidene bis (2-tert-butyl-5-methylphenol) diphosphite tetra (tridecyl) ester, 1, 3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane triphosphite hexa (tridecyl) ester, biphenylene diphosphonite tetra (2, 4-di-tert-butylphenyl) ester, 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, tris (2- [ (2, 4,8, 10-tetra-tert-butyldibenzo [ d), f ] [1,3,2] dioxaphosphepin-6-yl) oxy ] ethyl) amine, and the like.

Examples of the thioether light stabilizer (thioether compound) include: dialkyl thiodipropionate compounds such as dilauryl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate and the like; beta-alkylmercaptopropionate compounds of polyhydric alcohols such as tetrakis [ methylene (3-dodecylthio) propionate ] methane.

Examples of the amine light stabilizer (amine compound) include: polymers of dimethyl succinate with 4-hydroxy-2, 6-tetramethyl-1-piperidineethanol (trade name "TINUVIN 622", manufactured by BASF corporation), polymers of dimethyl succinate with 4-hydroxy-2, 6-tetramethyl-1-piperidineethanol and N, N ', N ", 1:1 reaction product of N ' -tetrakis (4, 6-bis (butyl- (N-methyl-2, 6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4, 7-diazadecane-1, 10-diamine (trade name" TINUVIN 119", manufactured by BASF corporation), dibutylamine/1, 3, 5-triazine/N, polycondensates of N ' -bis (2, 6-tetramethyl-4-piperidinyl) -1, 6-hexamethylenediamine and N- (2, 6-tetramethyl-4-piperidinyl) butylamine (trade name" TINUVIN 2020", manufactured by BASF corporation), poly [ {6- (1, 3-tetramethylbutyl) amino-1, 3, 5-triazine-2, 4-diyl } {2, 6-tetramethyl-4-piperidinyl } imino ] hexamethylene { (2, 6-tetramethyl-4-piperidinyl) imino } (trade name" TINUVIN 944", manufactured by BASF corporation), a mixture of bis (1, 2, 6-pentamethyl-4-piperidinyl) sebacate and methyl sebacate 1,2, 6-pentamethyl-4-piperidinyl ester (trade name" TINUVIN 765", manufactured by BASF corporation), bis (2, 6-tetramethyl-4-piperidinyl) sebacate (trade name "TINUVIN 770", manufactured by BASF corporation), bis (2, 6-tetramethyl-1- (octyloxy) -4-piperidinyl) sebacate, the reaction product of 1, 1-dimethylethyl hydroperoxide with octane (trade name "TINUVIN 123", BASF corporation), [ [3, 5-bis (1, 1-dimethylethyl) -4-hydroxyphenyl ] methyl ] butylmalonate bis (1, 2, 6-pentamethyl-4-piperidinyl) ester (trade name "TINUVIN 144", manufactured by BASF corporation), a reaction product of cyclohexane and N-butyl-2, 6-tetramethyl-4-piperidinamine-2, 4, 6-trichloro-1, 3, 5-triazine peroxide with 2-aminoethanol (trade name "TINUVIN 152", manufactured by BASF corporation), a mixture of bis (1, 2, 6-pentamethyl-4-piperidinyl) sebacate and methyl sebacate 1,2, 6-pentamethyl-4-piperidinyl ester (trade name "TINUVIN 292", BASF corporation), mixed esters of 1,2,3, 4-butanetetracarboxylic acid with 1,2, 6-pentamethyl-4-piperidinol and 3, 9-bis (2-hydroxy-1, 1-dimethylethyl) -2,4,8, 10-tetraoxaspiro [5.5] undecane (trade name "ADK STAB LA-63P", manufactured by ADEKA corporation), and the like. As the amine stabilizer, a hindered amine stabilizer is particularly preferable.

When the adhesive layer of the present invention contains a light stabilizer, the content of the light stabilizer in the adhesive layer of the present invention (particularly, the acrylic adhesive layer) is not particularly limited, and the content of the light stabilizer is preferably 0.1 part by weight or more, more preferably 0.2 part by weight or more, based on 100 parts by weight of the base polymer, from the viewpoint of easily exhibiting light resistance. In addition, from the viewpoint of preventing coloration due to the light stabilizer itself and easily obtaining high transparency and optical characteristics, the upper limit of the content of the light stabilizer is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, relative to 100 parts by weight of the base polymer.

The formation of the adhesive layer of the present invention is not particularly limited, and a crosslinking agent may be used. For example, the acrylic polymer in the acrylic adhesive layer can be crosslinked to control the gel fraction. The crosslinking agent may be used alone or in combination of two or more.

The crosslinking agent is not particularly limited, and examples thereof include: isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, amine-based crosslinking agents, and the like. Among them, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferable, and isocyanate-based crosslinking agents are more preferable.

Examples of the isocyanate-based crosslinking agent (polyfunctional isocyanate compound) include: lower aliphatic polyisocyanates such as 1, 2-ethylene diisocyanate, 1, 4-butylene diisocyanate, and 1, 6-hexamethylene diisocyanate; alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated xylene diisocyanate; aromatic polyisocyanates such as 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, 4' -diphenylmethane diisocyanate, and xylylene diisocyanate. Examples of the isocyanate-based crosslinking agent include: trimethylolpropane/toluene diisocyanate adduct (trade name "Coronate L", manufactured by Japanese polyurethane Co., ltd.), trimethylolpropane/hexamethylene diisocyanate adduct (trade name "Coronate HL", manufactured by Japanese polyurethane Co., ltd.), trimethylolpropane/xylylene diisocyanate adduct (trade name "Takenate D-110N", manufactured by Mitsui chemical Co., ltd.), and the like.

Examples of the epoxy-based crosslinking agent (polyfunctional epoxy compound) include: n, N' -tetraglycidyl m-xylylenediamine, diglycidyl aniline, 1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane, 1, 6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, tris (2-hydroxyethyl) isocyanurate triglycidyl ester, resorcinol diglycidyl ether, bisphenol S diglycidyl ether, epoxy resins having 2 or more epoxy groups in the molecule, and the like. Further, examples of the epoxy-based crosslinking agent include commercial products such as "tetra C" (manufactured by mitsubishi gas chemical Co., ltd.).

In the case of using the crosslinking agent in the formation of the adhesive layer of the present invention, the amount of the crosslinking agent used is not particularly limited, but is preferably 0.001 parts by weight or more, more preferably 0.01 parts by weight or more, based on 100 parts by weight of the base polymer, from the viewpoint of obtaining sufficient adhesive reliability. The upper limit of the amount of the crosslinking agent to be used is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, based on 100 parts by weight of the base polymer, from the viewpoints of obtaining moderate flexibility and improving the adhesive force of the adhesive layer, and easily controlling the various properties of the adhesive layer (in particular, strain amount a, strain amount B, recovery rate, glass transition temperature, etc.) within a predetermined range.

The adhesive layer (particularly, acrylic adhesive layer) of the present invention may contain a silane coupling agent from the viewpoint of improving the adhesion reliability under humidified conditions, particularly, the adhesion reliability to glass. The silane coupling agent may be used alone or in combination of two or more. When the adhesive layer contains a silane coupling agent, adhesiveness under wet conditions, particularly adhesiveness to glass, can be improved.

The silane coupling agent is not particularly limited, and examples thereof include: gamma-glycidoxypropyl trimethoxysilane, gamma-glycidoxypropyl methyl triethoxysilane, gamma-aminopropyl trimethoxysilane, N-phenylaminopropyl trimethoxysilane, and the like. Further, as the silane coupling agent, for example, there may be mentioned: trade name "KBM-403" (manufactured by Xinyue chemical Co., ltd.). Among them, the silane coupling agent is preferably gamma-glycidoxypropyl trimethoxysilane.

When the pressure-sensitive adhesive layer of the present invention contains a silane coupling agent, the content of the silane coupling agent in the pressure-sensitive adhesive layer (particularly, acrylic pressure-sensitive adhesive layer) of the present invention is not particularly limited, but the content of the silane coupling agent is preferably 0.01 parts by weight or more, more preferably 0.02 parts by weight or more, based on 100 parts by weight of the base polymer. The upper limit of the content of the silane coupling agent is preferably 1 part by weight or less, more preferably 0.5 part by weight or less, based on 100 parts by weight of the base polymer.

The adhesive layer of the present invention may contain an antistatic agent. The antistatic agent may be used alone or in combination of two or more. When the pressure-sensitive adhesive layer contains an antistatic agent, breakage of an adherend such as an image display panel can be prevented.

The antistatic agent may be: cationic antistatic agents having cationic functional groups such as quaternary ammonium salts, pyridinium salts, primary amine groups, secondary amine groups, and tertiary amine groups; an anionic antistatic agent having an anionic functional group such as sulfonate, sulfate, phosphonate, or phosphate; amphoteric ion antistatic agents such as alkyl betaine and its derivatives, imidazoline and its derivatives, and alanine and its derivatives; amino alcohol and its derivatives, glycerol and its derivatives, polyethylene glycol and its derivatives, and other nonionic antistatic agents; and an ion-conductive polymer obtained by polymerizing or copolymerizing a monomer having the above cationic, anionic, or zwitterionic ion-conductive group.

When the pressure-sensitive adhesive layer of the present invention contains an antistatic agent, the content of the antistatic agent in the pressure-sensitive adhesive layer of the present invention is not particularly limited, but the content of the antistatic agent is preferably 0.01 parts by weight or more, more preferably 0.02 parts by weight or more, based on 100 parts by weight of the base polymer. The upper limit of the content of the antistatic agent is preferably 1 part by weight or less, more preferably 0.5 part by weight or less, based on 100 parts by weight of the base polymer.

The adhesive layer of the present invention may contain a colorant. The colorant may be used alone or in combination of two or more. When the adhesive layer contains a colorant, it is preferable from the viewpoint of being able to prevent reflection caused by metal wiring, ITO wiring, or the like disposed on the substrate of the image display device of the present invention.

The colorant may be a dye or a pigment as long as it is soluble or dispersible in the adhesive layer of the present invention. Dyes are preferred in that even a small amount of the dye can achieve low haze and is easily and uniformly distributed without having sedimentation properties as pigments do. In addition, pigments are preferable in terms of high color rendering properties even when added in small amounts. In the case of using a pigment as a colorant, a pigment having low conductivity or no conductivity is preferable. In the case of using a dye, it is preferable to use the above-mentioned light stabilizer in combination.

As the colorant, a colorant that exhibits transmittance to ultraviolet rays (wavelength of 330nm to 400 nm) or a colorant that exhibits absorbance to ultraviolet rays can be used without limitation as long as it absorbs visible light (wavelength of 400nm to 700 nm), and a colorant that absorbs visible light and has ultraviolet transmittance is preferable. That is, the colorant is preferably a colorant having a maximum transmittance of 330nm to 400nm at a wavelength greater than a maximum transmittance of 400nm to 700nm at a wavelength. The colorant is preferably a colorant having an average transmittance of 330nm to 400nm greater than an average transmittance of 400nm to 700 nm. The transmittance of the colorant is measured using a solution or dispersion in which a suitable solvent or dispersion medium (an organic solvent having a small absorption in the range of 330nm to 700 nm) such as Tetrahydrofuran (THF) or the like is used so that the transmittance at a wavelength of 400nm is about 50% to about 60%.

The absorption of ultraviolet rays of carbon black or titanium black, which is generally used as a black colorant, is greater than the absorption of visible light (ultraviolet transmittance is less than visible light transmittance). Therefore, when a colorant such as carbon black is added to the active energy ray-curable acrylic pressure-sensitive adhesive composition, most of the ultraviolet light irradiated for photocuring is absorbed by the colorant, the amount of light absorbed by the photopolymerization initiator is small, and the time required for photocuring (the cumulative irradiation light amount increases). In addition, when the thickness of the adhesive layer is large, ultraviolet rays reaching the surface opposite to the light irradiation surface are small, and thus, there is a tendency that the light irradiation and the photo-curing are insufficient even when the light irradiation is performed for a long time. In contrast, by using a colorant having a transmittance of ultraviolet rays higher than that of visible light, curing inhibition by the colorant can be suppressed.

Examples of the black pigment having ultraviolet transmittance include: "9050BLACK", "UVLK-0001", manufactured by Tokushiki Co., ltd. Examples of the ultraviolet-absorbing black dye include: "VALIFAST BLACK 3810", "NUBIAN Black PA-2802", manufactured by Orient chemical industries, inc. Examples of the ultraviolet-absorbing black pigment include: carbon black, titanium black, and the like.

The content of the colorant in the pressure-sensitive adhesive layer of the present invention is, for example, about 0.01 to about 20 parts by weight based on 100 parts by weight of the base polymer, and may be appropriately set depending on the kind of the colorant, the color tone of the pressure-sensitive adhesive layer, the light transmittance, and the like. The colorant may be added to the composition in the form of a solution or dispersion in a suitable solvent.

The pressure-sensitive adhesive layer of the present invention may contain additives such as a crosslinking accelerator, a tackifying resin (rosin derivative, polyterpene resin, petroleum resin, oil-soluble phenol, etc.), an antioxidant, a filler, an antioxidant, a chain transfer agent, a plasticizer, a softener, and a surfactant, as necessary, within a range that does not impair the effects of the present invention. It should be noted that two or more such additives can be used singly or in combination.

The haze of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less from the viewpoints of appearance characteristics, transparency, and optical characteristics. In the present specification, the haze of the adhesive layer can be measured, for example, by using a haze meter according to JIS K7136.

The total light transmittance of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 85% or more, more preferably 90% or more, and even more preferably 92% or more from the viewpoints of appearance characteristics, transparency, and optical characteristics. In the present specification, the total light transmittance of the adhesive layer can be measured in accordance with JIS K7361-1 using a haze meter, for example. The total light transmittance is a transmittance of light (visible light) having a wavelength of 400nm to 780 nm.

The thickness of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 12 μm or more, more preferably 15 μm or more, still more preferably 20 μm or more, and particularly preferably 70 μm or more from the viewpoint of obtaining sufficient adhesive reliability. When the thickness is 12 μm or more, the pressure-sensitive adhesive layer is preferable from the viewpoint of sufficiently following shrinkage or expansion of the image display device of the present invention in the use environment and suppressing swelling or peeling. From the viewpoint of optical characteristics, the thickness is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less.

< manufacturing of adhesive tape for optical use >

The optical adhesive tape of the present invention can be produced by laminating the adhesive layer of the present invention on the first surface of the substrate of the present invention.

The method of laminating the adhesive layer of the present invention on the first surface of the substrate of the present invention is not particularly limited, and for example, the method can be performed as follows: coating (coating) the adhesive composition on a separator, and drying and curing the resulting adhesive composition layer; the adhesive composition is coated (applied) on the separator, and the obtained adhesive composition layer is cured by irradiation with active energy rays, thereby forming a sheet-like adhesive layer on the separator, and the adhesive layer is bonded to the first surface of the substrate of the present invention. Further, if necessary, the heat drying may be further performed.

In the case of curing by irradiation with active energy rays, it is preferable to further provide a spacer on the surface of the coating film, and irradiate active energy rays in a state in which the adhesive composition is sandwiched between two spacers, thereby preventing polymerization inhibition by oxygen.

Other methods for laminating the adhesive layer of the present invention on the first surface of the substrate of the present invention can be performed, for example, as follows: coating (coating) the adhesive composition on the first surface of the substrate of the present invention, and drying and curing the resulting adhesive composition layer; the adhesive composition is coated (coated) on the first surface of the substrate of the present invention, and the resulting adhesive composition layer is irradiated with an active energy ray to be cured. Further, if necessary, the heat drying may be further performed.

In the case of curing by irradiation with active energy rays, it is preferable to provide a spacer on the surface of the coating film, and to irradiate active energy rays in a state in which the adhesive composition is sandwiched between the substrate of the present invention and the spacer, thereby preventing polymerization inhibition by oxygen.

Before the irradiation with the active energy ray, the sheet-like coating film may be heated in order to remove the solvent or the like. In the case of removing the solvent or the like by heating, it is preferable to perform it before disposing the separator.

Examples of the active energy ray include: ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, electron rays and the like; ultraviolet rays and the like, and ultraviolet rays are particularly preferable. The irradiation energy, irradiation time, irradiation method, and the like of the active energy ray are not particularly limited.

The adhesive composition can be prepared by a known or conventional method. For example, the solvent-based acrylic adhesive composition can be produced by mixing an additive (for example, an ultraviolet absorber or the like) as necessary with a solution containing the acrylic polymer. For example, the active energy ray-curable acrylic pressure-sensitive adhesive composition can be produced by mixing an additive (for example, an ultraviolet absorber or the like) as necessary with the above-mentioned mixture of acrylic monomers or a partial polymer thereof.

The adhesive composition may be applied (coated) by a known coating method. For example, a gravure roll coater, a reverse roll coater, a roll lick coater, a dip roll coater, a bar coater, a blade coater, a spray coater, a comma coater, a direct coater, or the like may be used.

In particular, in the case of forming the adhesive layer using the active energy ray-curable adhesive composition, the active energy ray-curable adhesive composition preferably contains a photopolymerization initiator. When the active energy ray-curable adhesive composition contains an ultraviolet absorber, it is preferable that the photopolymerization initiator contains at least a photopolymerization initiator having light absorption characteristics in a wide wavelength range. For example, it is preferable to include at least a photopolymerization initiator having light absorption characteristics in the visible light range in addition to light absorption characteristics in the ultraviolet light range. This is because there is a concern that curing by active energy rays is hindered by the action of the ultraviolet absorber, and when a photopolymerization initiator having light absorption characteristics in a wide wavelength range is contained, the adhesive composition is likely to obtain high photocurability.

< antistatic layer >)

In the optical adhesive tape of the present invention, an antistatic layer may be provided on the surface or between any layers. The optical pressure-sensitive adhesive tape of the present invention has an antistatic layer, and thus can prevent breakage of an adherend such as an image display panel. The antistatic layer is preferably formed between the substrate of the present invention and the adhesive layer of the present invention.

The antistatic layer is not particularly limited, and is formed by applying a conductive coating liquid containing a conductive polymer to a separator. Specifically, for example, an antistatic layer is formed by coating a conductive coating liquid containing a conductive polymer on the first surface of the substrate of the present invention. Specific coating methods include: roll coating, bar coating, gravure coating, and the like.

Examples of the conductive polymer include: conductive polymers doped with polyanion in pi conjugated system conductive polymers, and the like. As the pi conjugated system conductive polymer, there can be mentioned: polythiophene, polypyrrole, polyaniline, polyacetylene, and the like. As the polyanion, there may be mentioned: polystyrene sulfonic acid, polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallylsulfonic acid, polyethyl acrylate sulfonic acid, polymethacrylic acid, and the like.

The thickness of the antistatic layer is preferably 1nm to 1000nm, more preferably 5nm to 900nm. The antistatic layer may be provided in one layer or two or more layers.

< spacer >

In the optical adhesive tape of the present invention, the surface of the adhesive layer of the present invention (the adhesive surface of the adhesive layer of the present invention) can be protected by a spacer until the time of use. The spacer is used as a protective material for the adhesive layer, and is peeled off when the optical adhesive tape of the present invention is attached to an adherend.

As the separator, a conventional release paper or the like can be used, and specifically, for example, a substrate having a release treatment layer formed of a release treatment agent on at least one surface, a low-tackiness substrate containing a fluorine-containing polymer (for example, polytetrafluoroethylene, chlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinyl chloride-vinylidene fluoride copolymer or the like), a low-tackiness substrate containing a nonpolar polymer (for example, an olefin resin such as polyethylene, polypropylene or the like), or the like can be used.

As the separator, for example, a separator having a release treatment layer formed on at least one surface of a separator base material can be suitably used. Examples of such a separator substrate include: plastic base materials (synthetic resin films) such as polyester films (polyethylene terephthalate films and the like), olefin resin films (polyethylene films, polypropylene films and the like), polyvinyl chloride films, polyimide films, polyamide films (nylon films), rayon films and the like, papers (fine papers, japanese papers, kraft papers, cellophane, synthetic papers, surface-coated papers and the like); and a substrate (2-layer to 3-layer composite) obtained by layering them by lamination, coextrusion, or the like.

The release agent constituting the release layer is not particularly limited, and for example, a silicone release agent, a fluorine-containing release agent, a long-chain alkyl release agent, and the like can be used. The peeling agent may be used alone or in combination of two or more.

The thickness of the spacer is not particularly limited and may be appropriately selected from the range of 5 μm to 100 μm.

In order to prevent breakage of an adherend such as an image display panel, the separator may be provided with an antistatic layer on at least one surface of the separator substrate. The antistatic layer may be formed on one surface (the release treated surface or the untreated surface) of the separator, or may be formed on both surfaces (the release treated surface and the untreated surface) of the separator.

The antistatic layer is not particularly limited, and is formed by applying a conductive coating liquid containing a conductive polymer to a separator. Specifically, for example, an antistatic layer is formed by applying a conductive coating liquid containing a conductive polymer onto a separator (a release treated surface and/or an untreated surface). Specific coating methods include: roll coating, bar coating, gravure coating, and the like.

As the conductive polymer, the same conductive polymer as the conductive polymer constituting the antistatic layer of the optical adhesive tape of the present invention can be used.

< surface protective film >)

In the optical adhesive tape of the present invention, the second surface of the substrate of the present invention may be protected by a surface protective film. The surface protective film is used as a protective material for the second surface of the substrate of the present invention when the optical adhesive tape of the present invention, the image display device of the present invention, and the tiled display of the present invention are manufactured or transported.

As a material for forming the surface protective film, there can be mentioned: ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, copolymer resins thereof, and the like. Ester resins (particularly polyethylene terephthalate resins) are preferred.

The thickness of the surface protective film is typically 20 μm to 250. Mu.m, preferably 30 μm to 150. Mu.m.

The surface protective film is releasably attached to the second surface of the substrate of the present invention by any suitable adhesive. The surface protective film on which the adhesive layer is formed is preferably formed and bonded to the second surface of the substrate of the present invention of the optical adhesive tape of the present invention. Examples of the binder used for lamination of the surface protective film include: an adhesive composition comprising an acrylic resin, a styrene resin, a silicone resin, or the like as a base resin and a crosslinking agent selected from an isocyanate compound, an epoxy compound, an aziridine compound, or the like, and a silane coupling agent, or the like, blended in the base resin. The thickness of the adhesive layer is usually 1 μm to 60. Mu.m, preferably 3 μm to 30. Mu.m. If the pressure-sensitive adhesive layer is too thin, there is a possibility that the pressure-sensitive adhesive layer may be degraded and air bubbles may be easily mixed in, and if the pressure-sensitive adhesive layer is too thick, there is a possibility that the pressure-sensitive adhesive layer may protrude. From the viewpoints of chemical resistance, adhesion, and the like, an acrylic adhesive is preferably used.

< image display device >)

The image display device of the present invention has a laminated structure in which the optical pressure-sensitive adhesive tape of the present invention and the image display panel are laminated. In fig. 3, the image display device 20 has an image display panel 4 laminated on the adhesive layer 1 of the optical adhesive tape 10B.

The image display device of the present invention has the optical adhesive tape of the present invention in a laminated structure, and therefore can suppress shrinkage or expansion in the use environment and can maintain transparency unchanged. In addition, the pressure-sensitive adhesive layer of the present invention sufficiently follows the shrinkage or expansion of the image display device, and thus is less likely to bulge or peel. In addition, in the case where there is a level difference in the uneven shape due to wiring or the like on the image display panel, the pressure-sensitive adhesive layer of the present invention sufficiently follows the level difference, and can be filled without leaving bubbles or the like.

The image display panel is not particularly limited, and examples thereof include: a liquid crystal image display panel, a self-luminous image display panel (e.g., an organic EL (electroluminescence) image display panel, an LED image display panel), and the like.

The image display panel is formed by alternately arranging RGB elements, and it is preferable that Black Matrixes (BM) are filled between the RGB elements in order to improve contrast.

The image display device of the present invention may have an optical member other than the optical adhesive tape of the present invention and the image display panel on the surface or between any layers. The optical member is not particularly limited, and examples thereof include: polarizing plates, phase difference plates, antireflection films, viewing angle adjusting films, optical compensation films, and the like. The optical member includes a member (a design film, a decorative film, a surface protection plate, etc.) which plays a role in decoration and protection while maintaining visibility of an image display device and an input device.

The image display device of the present invention can be manufactured by bonding the image display panel and the pressure-sensitive adhesive layer of the optical pressure-sensitive adhesive tape of the present invention.

Specifically, the image display panel and the optical adhesive tape of the present invention can be bonded by laminating them under heat and/or pressure. The curing may be performed by irradiation with active energy rays after lamination under heat and/or pressure. Irradiation with active energy rays can be performed in the same manner as the formation of the adhesive layer of the present invention.

< tiled display >)

The tiled display of the present invention is formed by arranging a plurality of image display devices of the present invention. In fig. 4, the tiled display 30 is formed by arranging 9 image display devices 20 (laminated structure is not shown) in a 3×3 array on a support substrate 31 in a tile shape, and the image display devices 20 are in contact with each other with a gap 32. As the support substrate, a glass plate and a plastic film similar to the base material of the present invention can be used.

Since the image display device of the present invention suppresses shrinkage or expansion in the use environment, a gap or overlap is less likely to occur between the plurality of image display devices in the tiled display of the present invention, the gap is less likely to become noticeable, and a good appearance is maintained. In addition, shrinkage or expansion is small, and transparency can be kept unchanged. In addition, the adhesive layer of the present invention can sufficiently follow the shrinkage or expansion of the image display device, and thus can prevent the occurrence of defects due to swelling or peeling.

In the tiled display according to the present invention, when the second surface of the substrate according to the present invention is subjected to an antireflection treatment and/or an antiglare treatment, it is preferable from the viewpoint of being able to prevent reflection due to metal wiring, ITO wiring, or the like disposed on the substrate of the image display device according to the present invention. In addition, it is also preferable from the viewpoint that the gap between the image display devices of the present invention is not easily visually recognized in the tiled display.

The tiled display of the present invention may have members other than the image display device of the present invention and the above-described support substrate. Such a member is not particularly limited, and examples thereof include: backlight, touch sensor, etc.

The tiled display of the present invention can be manufactured by arranging a plurality of image display devices of the present invention on the support substrate without any gap, and fixing them by sealing the outermost surface with glass or the like.

Examples

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Production example 1

(preparation of antiglare film 1)

[ preparation of coating liquid for Forming anti-glare layer 1 ]

40 parts by weight of an ultraviolet curable urethane acrylate resin (trade name "NK Oligo UA-53H-80BK", manufactured by new middle village chemical Co., ltd.), 57.5 parts by weight of a multifunctional acrylate containing pentaerythritol triacrylate as a main component (manufactured by osaka organic chemical Co., ltd., trade name "Viscoat # 300"), 2.5 parts by weight of a diluent of a composition for an optical adjustment layer containing zirconia particles and an ultraviolet curable resin ("OPSTAR Z7540", manufactured by JSR corporation), 2.8 parts by weight of silicone particles (trade name "Tospearl 130ND", manufactured by michaux high new material japan), 2.5 parts by weight of an organoclay as a thixotropic agent, namely, synthetic montmorillonite (manufactured by Kunimine industrial Co., ltd., trade name "Smecton SAN"), 3 parts by weight of a photopolymerization initiator (manufactured by BASF corporation, trade name "nilad"), 6.5 parts by weight of crosslinked styrene-co-polymer particles (manufactured by BASF corporation, trade name "3.907") and (manufactured by leveling agent "0.907 by chemical Co., ltd.") were mixed. The organoclay was diluted with toluene so that the solid content was 6% by weight, and then used. The mixture was diluted with a toluene/Cyclopentanone (CPN) mixed solvent (weight ratio 64/36) so that the solid content concentration was 38 wt%, and an antiglare layer forming material (coating liquid) was prepared using an ultrasonic disperser.

[ formation of antiglare layer 1 ]

A transparent plastic film base material (PET film, trade name "38U413", thickness: 38 μm) was prepared as a base material. The anti-glare layer forming material (coating liquid) was coated on the transparent plastic film using a wire barA coating film is formed on one surface of the substrate (coating step). Subsequently, the coating film was dried by heating at 95℃for 1 minute (drying step). Then, the cumulative light amount was 300mJ/cm by irradiation with a high-pressure mercury lamp ² The above-mentioned coating film was subjected to a curing treatment by ultraviolet rays, thereby forming an antiglare layer having a thickness of 6.5. Mu.m. In this way, a laminate of the light-transmitting base material and the antiglare layer 1 was obtained.

[ preparation of coating liquid for Forming antireflection layer 1 ]

100 parts by weight of a multifunctional acrylate (trade name "Viscoat #300 manufactured by Osaka organic chemical Co., ltd.), 100 parts by weight of silica hollow nanoparticles (trade name" THRULYA 5320 manufactured by Nitro catalyst chemical Co., ltd.), 40 parts by weight of silica solid nanoparticles (trade name "MIBK-ST", manufactured by Nitro chemical Co., ltd.), 12 parts by weight of an additive containing fluorine element (trade name "KY-1203 manufactured by Xinyue chemical Co., ltd.), 5 parts by weight of a photopolymerization initiator (trade name" OMNIRAD 907 manufactured by BASF Co., ltd.), and 5 parts by weight of a photopolymerization initiator (trade name "OMNIRAD 2959") were mixed. To this mixture was added MIBK (methyl isobutyl ketone) and PMA (propylene glycol monomethyl ether acetate) at 70: the mixed solvent obtained by mixing at a weight ratio of 30 was used as a diluting solvent so that the solid content of the whole became 1.5% by weight, and stirred, thereby preparing a coating liquid for forming an antireflection layer.

[ formation of antireflection layer 1 ]

The antireflection layer-forming coating liquid is coated on the antiglare layer surface of the laminate of the light-transmitting substrate and the antiglare layer 1 by a winding rod (coating step). The above-mentioned applied coating liquid was heated at 80 ℃ for 1 minute to be dried, thereby forming a coating film (drying step). The film after drying was irradiated with a high-pressure mercury lamp with an accumulated light quantity of 300mJ/cm ² Is subjected to a curing treatment (curing step). Thereby curing the coating film to form a thicknessAn antireflection layer 1 of 0.1 μm (antireflection layer forming step). The antiglare film 1 of this production example 1 was produced in the above manner.

Production example 2

(preparation of antiglare film 2)

[ formation of antiglare layer 2 ]

A laminate of the light-transmitting substrate and the antiglare layer 2 was produced in the same manner as in production example 1, except that the amount of the multifunctional acrylate containing pentaerythritol triacrylate as a main component was changed to 60 parts by weight, the amount of the silicone particles was changed to 0.9 parts by weight, the amount of the organoclay as a thixotropic agent, that is, the amount of the synthetic montmorillonite was changed to 1.5 parts by weight, and the diluent of the composition for an optical adjustment layer containing zirconia particles and an ultraviolet-curable resin and the fine particles of the crosslinked acrylic-styrene copolymer resin were not used in the preparation of the coating liquid for antiglare layer.

[ formation of antireflection layer 2 ]

An antireflection layer 2 was formed in the same manner as in production example 1, except that the amount of silica hollow nanoparticles to be mixed was changed to 240 parts by weight in the preparation of the coating liquid for antireflection layer formation. The antiglare film 2 of this production example 2 was produced in the above manner.

Production example 3

(preparation of antiglare film 3)

An antiglare film 3 of this production example 3 was produced in the same manner as in production example 1, except that a transparent plastic film base material (COP film, trade name "ZF14", manufactured by japan rayleigh Weng Zhushi, thickness: 50 μm) was used as the base material in the formation of the antiglare layer.

Production example 4

(preparation of antiglare film 4)

An antiglare film 4 of this production example 4 was produced in the same manner as in production example 1, except that a transparent plastic film base material (PEN film, trade name "Q51", thickness: 25 μm) was used as the base material for the formation of the antiglare layer.

Production example 5

(preparation of antiglare film 5)

An antiglare film 5 of this production example 5 was produced in the same manner as in production example 1, except that a transparent plastic film base material (PEEK film, trade name "EXPEEK", thickness: 50 μm) was used as a base material in the formation of the antiglare layer.

Production example 6

(production of transparent Plastic film substrate)

For 81.98 parts by mass of isosorbide (hereinafter, abbreviated as "ISB" in some cases), 47.19 parts by mass of tricyclodecane dimethanol (hereinafter, abbreviated as "TCDDM" in some cases), 175.1 parts by mass of diphenyl carbonate (hereinafter, abbreviated as "DPC" in some cases) and 0.979 parts by mass of cesium carbonate 0.2 mass% aqueous solution as a catalyst were charged into a reaction vessel, and the reaction vessel was heated to 150 ℃ as a first step of the reaction under a nitrogen atmosphere, and the raw materials were dissolved (about 15 minutes) while stirring was performed as needed. Then, the pressure was adjusted from normal pressure to 13.3kPa, the temperature of the heating tank was raised to 190℃over 1 hour, and the produced phenol was withdrawn out of the reaction vessel. The whole reaction vessel was kept at 190℃for 15 minutes, and then, as a step of the second stage, the pressure in the reaction vessel was adjusted to 6.67kPa, the temperature of the heating tank was raised to 230℃over 15 minutes, and the produced phenol was withdrawn out of the reaction vessel. Since the stirring torque of the stirrer was increased, the temperature was raised to 250℃in 8 minutes, and then the pressure in the reaction vessel was set to 0.200kPa or less in order to remove the produced phenol. After a predetermined stirring torque is reached, the reaction is terminated, and the resultant reaction product is extruded into water, whereby pellets of the polycarbonate resin are obtained. The obtained polycarbonate resin was dried under vacuum at 80℃for 5 hours, and then a transparent plastic film substrate composed of a polycarbonate resin was produced with a thickness of 40 μm using a film-forming apparatus having a single screw extruder (manufactured by Zhi Pu mechanical Co., ltd., cylinder set temperature: 250 ℃), T-die (width 300mm, set temperature: 250 ℃), cooling rolls (set temperature: 120 ℃ C. About.130 ℃ C.) and a winder.

(preparation of antiglare film 6)

An antiglare film 6 of this production example 6 was produced in the same manner as in production example 1, except that the transparent plastic film base material made of a polycarbonate resin obtained as described above was used as a base material in the formation of the antiglare layer.

PREPARATION EXAMPLE 7

(preparation of antiglare film 7)

An antiglare film 7 of this production example 7 was produced in the same manner as in production example 1, except that a transparent plastic film base material (CPI film, manufactured by KOLON corporation, trade name "c_50_d", thickness: 50 μm) was used as the base material in the formation of the antiglare layer.

Production example 8

(preparation of antiglare film 8)

An antiglare film 8 of this production example 8 was produced in the same manner as in production example 1, except that a transparent plastic film base material (TAC film, trade name "TD80UL", thickness: 80 μm) was used as the base material in the formation of the antiglare layer.

Production example 9

(preparation of acrylic adhesive composition 1)

[ preparation of acrylic oligomer ]

60 parts by weight of tetrahydrodicyclopentadiene methacrylate (DCPMA) and 40 parts by weight of Methyl Methacrylate (MMA) as monomer components, 3.5 parts by weight of alpha-thioglycerol as a chain transfer agent and 100 parts by weight of toluene as a polymerization solvent were mixed and stirred at 70℃for 1 hour under a nitrogen atmosphere. Next, 0.2 parts by weight of 2,2' -Azobisisobutyronitrile (AIBN) as a thermal polymerization initiator was charged, reacted at 70℃for 2 hours, then heated to 80℃and reacted for 2 hours. Then, the reaction solution was heated to 130 ℃ and dried to remove toluene, chain transfer agent and unreacted monomers, thereby obtaining a solid acrylic oligomer (acrylic oligomer a). The acrylic oligomer A had a weight average molecular weight of 5100 and a glass transition temperature (Tg) of 130 ℃.

[ preparation of prepolymer and acrylic adhesive composition 1 ]

60 parts by weight of Lauryl Acrylate (LA), 22 parts by weight of 2-ethylhexyl acrylate (2 EHA), 8 parts by weight of 4-hydroxybutyl acrylate (4 HBA) and 10 parts by weight of N-vinyl-2-pyrrolidone (NVP) as a monomer component for forming a prepolymer, and 0.1 part by weight of "Omnirad 184" manufactured by BASF corporation and 0.1 part by weight of "Omnirad651" manufactured by BASF corporation as a photopolymerization initiator were blended and irradiated with ultraviolet rays to polymerize the resulting mixture, thereby obtaining a prepolymer composition. To 100 parts by weight of the above prepolymer composition were added 37 parts by weight of 2-ethylhexyl acrylate (2 EHA) as a post-addition component, 0.08 part by weight of 1, 6-hexanediol diacrylate (trade name "A-HD-N", manufactured by Xinzhou Chemie Co., ltd.), 6 parts by weight of the above acrylic oligomer A, and 0.3 part by weight of a silane coupling agent (KBM 403, manufactured by Xinyue Chemie Co., ltd.), and then they were uniformly mixed, thereby preparing an acrylic adhesive composition 1.

Production example 10

(preparation of prepolymer and acrylic adhesive composition 2)

67 parts by weight of Butyl Acrylate (BA), 14 parts by weight of cyclohexyl acrylate (Viscoat #155 manufactured by Osaka organic chemical Co., ltd.) and 19 parts by weight of 4-hydroxybutyl acrylate (4 HBA), and 0.09 part by weight of "Omnirad 184 manufactured by BASF corporation and 0.09 part by weight of" Omnirad651 manufactured by BASF corporation as photopolymerization initiators were blended and polymerized by irradiation of ultraviolet rays, thereby obtaining a prepolymer composition. To 100 parts by weight of the above prepolymer composition were added 9 parts by weight of hydroxyethyl acrylate (HEA), 8 parts by weight of 4-hydroxybutyl acrylate (4 HBA), 0.02 parts by weight of dipentaerythritol hexaacrylate (DPHA), 0.3 parts by weight of a photopolymerization initiator ("Omnirad 651" manufactured by BASF corporation) and 0.35 parts by weight of a silane coupling agent ("KBM 403" manufactured by Xinyue chemical Co., ltd.) as post-addition components, and then they were uniformly mixed, thereby preparing an acrylic adhesive composition 2.

Production example 11

(preparation of prepolymer and acrylic adhesive composition 3)

78 parts by weight of 2-ethylhexyl acrylate (2 EHA), 4 parts by weight of hydroxyethyl acrylate (HEA) and 18 parts by weight of N-vinyl-2-pyrrolidone (NVP) as a monomer component for forming a prepolymer, and 0.035 parts by weight of "Omnirad 184" manufactured by BASF corporation and 0.035 parts by weight of "Omnirad651" manufactured by BASF corporation as a photopolymerization initiator were blended and irradiated with ultraviolet rays to polymerize the resulting prepolymer composition. To 100 parts by weight of the above prepolymer composition were added 17.6 parts by weight of hydroxyethyl acrylate (HEA) as a post-addition component, 0.294 parts by weight of 1, 6-hexanediol diacrylate (trade name "A-HD-N", manufactured by Xinzhou Chemie Co., ltd.), 11.8 parts by weight of the above acrylic oligomer A, and 0.35 parts by weight of a silane coupling agent (KBM 403, manufactured by Xinyue Chemie Co., ltd.), and then they were uniformly mixed, thereby preparing an acrylic adhesive composition 3.

Example 1

(preparation of substrate-less adhesive layer 1)

A polyethylene terephthalate (PET) film (manufactured by mitsubishi chemical corporation, "Diafoil MRF 75") having a thickness of 75 μm, which was provided with a silicone release layer on the surface, was used as a base material (double release film), and the acrylic adhesive composition 1 was applied to the release layer of the base material so as to have a thickness of 25 μm, thereby forming a coating layer. A release layer of a 75 μm thick PET film (manufactured by mitsubishi chemical corporation, "Diafoil MRE 75") having one side subjected to silicone release treatment was attached to the coated layer as a protective sheet (light release film). By using a lamp so that the irradiation intensity of the irradiation surface directly under the lamp is 5mW/cm ² The laminate was irradiated with ultraviolet rays from the protective sheet side by a black light lamp whose position was adjusted, and was photo-cured, whereby a base-material-free adhesive layer 1 having a thickness of 25 μm was obtained.

(preparation of adhesive tape 1)

An adhesive surface exposed by peeling one release film from the adhesive layer 1 without a base material obtained as described above was attached to a non-antiglare layer of the antiglare film 1 shown in production example 1, whereby an adhesive tape 1 comprising the antiglare film 1/the adhesive layer 1/the release film was obtained.

Example 2

(preparation of adhesive tape 2)

An adhesive tape 2 comprising the antiglare film 2, the adhesive layer 1 and the release film was obtained in the same manner as in example 1, except that the antiglare film 2 described above was used.

Example 3

(preparation of substrate-less adhesive layer 2)

A base-free adhesive layer 2 having a thickness of 25 μm was obtained in the same manner as in example 1, except that the acrylic adhesive composition 2 described above was used.

(preparation of adhesive tape 3)

An adhesive tape 3 comprising an antiglare film 1, an adhesive layer 2 and a release film was obtained in the same manner as in example 1, except that the adhesive layer 2 without a base material obtained as described above was used.

Example 4

(preparation of adhesive tape 4)

An adhesive tape 4 comprising the antiglare film 3, the adhesive layer 1 and the release film was obtained in the same manner as in example 1, except that the antiglare film 3 described above was used.

Example 5

(preparation of adhesive tape 5)

An adhesive tape 5 comprising the antiglare film 4, the adhesive layer 1 and the release film was obtained in the same manner as in example 1, except that the antiglare film 4 described above was used.

Example 6

(preparation of adhesive tape 6)

An adhesive tape 6 comprising the antiglare film 5, the adhesive layer 1 and the release film was obtained in the same manner as in example 1, except that the antiglare film 5 described above was used.

Example 7

(preparation of adhesive tape 7)

An adhesive tape 7 comprising the antiglare film 6, the adhesive layer 1 and the release film was obtained in the same manner as in example 1, except that the antiglare film 6 described above was used.

Example 8

(preparation of adhesive tape 8)

An adhesive tape 8 comprising the antiglare film 7, the adhesive layer 1 and the release film was obtained in the same manner as in example 1, except that the antiglare film 7 described above was used.

Comparative example 1

(preparation of adhesive tape 9)

An adhesive tape 9 comprising the antiglare film 8, the adhesive layer 1 and the release film was obtained in the same manner as in example 1, except that the antiglare film 8 described above was used.

Comparative example 2

(preparation of substrate-less adhesive layer 3)

A base-free adhesive layer 3 having a thickness of 25 μm was obtained in the same manner as in example 1, except that the acrylic adhesive composition 3 described above was used.

(preparation of adhesive tape 10)

An adhesive tape 10 comprising the antiglare film 8, the adhesive layer 3 and the release film was obtained in the same manner as in example 1, except that the antiglare film 8 and the adhesive layer 3 having no base material described above were used.

(evaluation)

The adhesive tapes obtained in the above examples and comparative examples were used for the following evaluation. The evaluation methods are as follows. The results are shown in table 2.

(1) Average dimensional change rate

The adhesive tapes prepared in each example and each comparative example were cut into a nearly square shape in plan view of 100mm in MD direction×100mm in TD direction, and scratches in a cross pattern were made at each of the 4 corners thereof, to thereby produce test pieces.

For the test piece before heating (25 ℃), a distance (length) between scratches (center of intersecting pattern) in the MD direction and a distance (length) between scratches in the TD direction were measured at room temperature (25 ℃) using a CNC three-dimensional measuring instrument (manufactured by Sanforg Co., ltd., "LEGEX 774"). Thus, the lengths before heating in the MD direction and the TD direction are obtained.

Then, the test piece was heated at 60℃under a relative humidity of 90% for 500 hours, and then naturally cooled at room temperature (25 ℃) for 1 hour. Then, the distance between the MD directions and the distance between the TD directions of the scratches were measured by using a CNC three-dimensional analyzer. Thereby, the heated lengths in the MD direction and the TD direction are obtained. Next, the dimensional change rates A1, A2 in the MD direction and the TD direction were calculated by the following formulas, and the average value thereof was taken as the average dimensional change rate (%). The ratio (A1/A2) of the dimensional change rate in the MD direction to the dimensional change rate in the TD direction was obtained.

Dimensional change rate (%) = [ length after heating (mm) -length before heating (mm) ]/length before heating (mm) ×100

Average dimensional change rate (%) = [ dimensional change rate in MD direction+dimensional change rate in TD direction ]/2

(2) Maximum amount of curl

The release films of the adhesive tapes prepared in each example and each comparative example were peeled off, a PET film (trade name "Diafoil T100E50" manufactured by mitsubishi chemical corporation) was attached, and the obtained laminate was cut into a nearly square shape in plan view of 100mm×100mm, to prepare test pieces.

Then, the test piece was heated at 60℃under a relative humidity of 90% for 500 hours, and then naturally cooled at room temperature (25 ℃) for 1 hour. Then, the sheet was placed on a horizontal plane with the surface of the curl protrusion being the lower side, and the distance from the horizontal plane was measured at 4 points of the corner, and the distance from the longest point of the horizontal plane was taken as the maximum curl amount (mm).

The maximum curl amount measured by placing the laminate on a horizontal plane with the PET film side of the laminate being the lower side is set to +, and the maximum curl amount measured by placing the laminate on a horizontal plane with the base material side of the laminate (the opposite side of the PET film) being the lower side is set to +.

(3) Reflectivity of

The adhesive faces of the adhesive tapes obtained in each example and each comparative example were attached to a black acrylic resin plate, and test pieces were produced. The obtained test piece was set on the side of an adhesive tape in a spectrophotometer U4100 (manufactured by hitachi high technology corporation) on the side of a light source, and the reflectance (%) in the visible light region of 5 ° specular reflection was measured.

(4) Haze degree

The adhesive tapes obtained in each example and each comparative example were measured at room temperature (23 ℃) using a haze measuring device (manufactured by color research, village, HR-100). The measurement was repeated 3 times, and the average value thereof was used as a measurement value.

(5) Strain amount a, strain amount B, and recovery rate

The spacers were peeled from the adhesive layers obtained in each of examples and comparative examples, and a plurality of adhesive layers were laminated to prepare a test specimen having a thickness of about 2mm, and the test specimen was punched out into a disk shape having a diameter of 7.9mm, and was used as a test specimen. The shear test for obtaining "strain A", "strain B" and "recovery" was performed as shown in FIG. 5. Specifically, using "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific company having parallel plates 41 and 42 with diameters of 7.9mm, the upper surface of the parallel plate 41 and the bottom surface of the parallel plate 42 are aligned with and in contact with the bottom surface and the upper surface of the adhesive layer of the sample, respectively (fig. 5 (b)). Next, dynamic viscoelasticity was measured under the following measurement conditions, the strain amount a at 500Pa and 600 seconds (fig. 5 (c)) was read, the strain amount B at 1800 seconds (fig. 5 (d)) was read, and the recovery rate was calculated by the following equation.

(measurement conditions)

Deformation mode: torsion

Measurement procedure: hold at 500Pa for 600 seconds and then at 0Pa for 1800 seconds.

Measuring temperature: 60 DEG C

Axial force: 0.2N

Recovery rate: (strain A-strain B)/strain A×100

(6) Storage modulus, loss tangent and glass transition temperature of adhesive layer

The separator was peeled from the adhesive layers obtained in each of examples and comparative examples, and a plurality of adhesive layers were laminated, thereby producing a test sample having a thickness of about 2 mm. The test specimen was punched into a disk shape having a diameter of 7.9mm, which was sandwiched between parallel plates, and dynamic viscoelasticity was measured under the following conditions using "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific company, and the storage modulus G' and the loss tangent tan δ at each temperature were read from the measurement results. In addition, the temperature at which tan δ reaches a maximum is taken as the glass transition temperature of the adhesive layer.

(measurement conditions)

Deformation mode: torsion

Measuring frequency: 1Hz

Measuring temperature: -70-150 DEG C

(7) Shear force of adhesive layer

The adhesive tapes obtained in each of examples and comparative examples were cut into a size of 10mm in width and 100mm in length, the separator was peeled off, and then the adhesive layer of the adhesive tape was used to give an adhesive (tacky) area of 1cm ² Is bonded to an acrylic resin plate (acrylic, mitsubishi chemical Co., ltd.) and pulled in the shear direction at 23℃at a peeling rate of 0.06 mm/min, and the maximum load (N/cm) ² ) As shear forces.

(8) 300% tensile residual stress value of adhesive layer

The adhesive layers obtained in each of examples and comparative examples were cut into a size of 40mm×40mm, and the separator on one side was peeled off, and then folded once so that the adhesive faces were bonded to each other, and the separator on one side was peeled off again, and the adhesive faces were bonded to each other again, thereby producing an adhesive layer sample having a size of about 10mm×40mm and a thickness of about 400 μm. The adhesive layer samples were set in a tensile tester in which the distance between the chucks was set to 20mm, and stretched at a stretching speed of 200 mm/min by 60mm (300%) (the distance between the chucks after stretching was 80 mm). The tensile strength was maintained at a position of 60mm for 300 seconds, and the stress value was measured thereafter, and "300% tensile residual stress value" was calculated by the following formula.

300% tensile residual stress value (N/cm) ² ) Stress value (N)/(N) after 300 sec of fixation retention(4X adhesive sheet thickness (mm)/10)

(9) Expansion rate of humidity

The adhesive tapes obtained in each of examples and comparative examples were cut into pieces having a width of 2mm in the TD direction and a length of 20mm in the MD direction, and were measured under the following conditions using HC-TMA4000SA manufactured by Bruker AXS Co., ltd.

(measurement conditions)

Deformation mode: stretching

Load: 2g

Holding time: 5 hours

Humidity rise rate: 5% RH/min

Measuring atmosphere: maintaining at 60deg.C and relative humidity of 30% until saturated, and controlling to 60deg.C and relative humidity of 60%

(10) Coefficient of humidity expansion of substrate

The coefficient of humidity expansion was determined by measuring the elongation of each film when the humidity was changed from 30% RH to 60% RH at 60℃using HC-TMA4000SA type manufactured by Bruker AXS, inc. (unit:/RH%). The coefficient of humidity expansion (α) is calculated by the following formula.

α＝ΔL/{(T2-T1)×L}

T1: determination of the coefficient of humidity expansion on the Low humidity side (% RH)

T2: determination of the humidity expansion coefficient of the high humidity side humidity (% RH)

Δl: the difference (μm) between the length of the test piece at T1 and the length at T2

L: length of test piece at room temperature (60 ℃ C.) (μm)

(11) Glass transition temperature (Tg) of the substrate

About 8mg of a sample was taken, placed in an aluminum container, and DSC measurement was performed.

The device comprises: manufactured by TA Instruments, Q-2000

A container: aluminum container

Temperature program: -30℃ to 300 DEG C

Heating rate: 10 ℃/min

Atmosphere gas: n (N) ₂ (50 ml/min)

(12) Gap confirmation between adhesive tapes

The adhesive tapes obtained in examples and comparative examples were cut into 5cm×5cm pieces, and then 4 pieces of the adhesive tape were attached to glass without any gap, heated at 60℃under an environment with a relative humidity of 90% for 500 hours, and then naturally cooled at room temperature (25 ℃) for 1 hour. Then, glass was placed on the backlight, and the gap between the adhesive tapes when the backlight was irradiated with light was visually evaluated on the basis of the following criteria.

The gaps between the adhesive tapes were not confirmed by o … ….

X … … confirm the gap between the adhesive tapes

(13) Adhesive peel confirmation

The end of the adhesive tape of the sample heated at 60℃for 500 hours under a relative humidity of 90% used for the confirmation of the gap between the adhesive tapes was confirmed by an optical microscope, and evaluated according to the following criteria.

No detachment of the adhesive tape was confirmed by o … ….

X … … confirmed the release of the adhesive tape

Hereinafter, modifications of the present invention will be described.

[ additional note 1] an optical adhesive tape having a laminated structure in which a base material having a first surface and a second surface and an adhesive layer laminated on the first surface of the base material are laminated,

the average dimensional change rate in the width direction and the longitudinal direction of the optical adhesive tape when the optical adhesive tape is heated for 500 hours at 60 ℃ under a relative humidity of 90%, is within + -0.15%, and

the recovery rate of the adhesive layer obtained in the shear test described below was 95% or less,

< shear test >)

The strain A (%) when 500Pa of shear force in 600 seconds of torsion direction was applied from above and below the disk-shaped adhesive layer having a thickness of 2mm and a diameter of 7.9mm at 60℃and the strain B (%) when 1800 seconds was thereafter held at 0Pa of shear force were measured, and the recovery (%) was calculated from the following formula,

Recovery (%) = (strain amount a-strain amount B)/strain amount a×100

The optical adhesive tape according to appendix 2, wherein the optical adhesive tape satisfies the following formula:

|C×D|≤3

in the above-mentioned method, the step of,

c is the average dimensional change rate [% ] in the width direction and in the longitudinal direction when the optical adhesive tape is heated for 500 hours in an environment of 60 ℃ and a relative humidity of 90%,

d is a laminate obtained by bonding the adhesive layer of the optical adhesive tape to a PET film having a thickness of 50 μm and cutting it to a square of 10cm, and the maximum curl amount [ mm ] of the laminate when the laminate is heated at 60 ℃ for 500 hours under an environment having a relative humidity of 90%,

The optical adhesive tape according to any one of appendixes 1 to 2, wherein the strain amount A of the adhesive layer is 3% or more.

[ additional note 4] the optical adhesive tape according to any one of additional notes 1 to 3, wherein the strain amount B of the adhesive layer is 0.1% or more.

[ additional note 5] the optical adhesive tape according to any one of additional notes 1 to 4, wherein the glass transition temperature (Tg) of the base material is 60℃or higher.

[ additional note 6] the optical adhesive tape according to any one of additional notes 1 to 5, wherein the adhesive layer has a glass transition temperature (Tg) of-10 ℃ or lower.

The optical adhesive tape according to any one of the above-mentioned items 1 to 6, wherein the thermal expansion coefficient when the optical adhesive tape is humidified from 60℃to 60℃with a relative humidity of 30% and a relative humidity of 60% is 0.1% or less.

[ additionally remembered 8 ]]The optical adhesive tape according to any one of supplementary notes 1 to 7, wherein the substrate has a coefficient of thermal expansion of 5X 10 ^-5 The following/%RH.

The optical adhesive tape according to any one of supplementary notes 9 to 1 to 8, wherein the second surface of the base material is subjected to an antireflection treatment and/or an antiglare treatment.

The optical adhesive tape according to any one of supplementary notes 10, wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer.

[ appendix 11] an image display device obtained by laminating an image display panel and the optical adhesive tape according to any one of appendixes 1 to 10.

Note 12 a tiled display obtained by arranging the image display devices described in note 11.

Description of the reference numerals

10A, 10B optical pressure-sensitive adhesive tape

1. Substrate material

1a first side of the substrate

1b second side of the substrate

2. Adhesive layer

3. Antireflection treatment and/or antiglare treatment

20. Image display device

4. Image display panel

30. Spliced display

31. Support substrate

40. Adhesive layer

41. 42 parallel plates

Claims

1. An optical adhesive tape having a laminated structure in which a base material having a first surface and a second surface and an adhesive layer laminated on the first surface of the base material,

the average dimensional change rate in the width direction and the longitudinal direction of the optical adhesive tape when the optical adhesive tape is heated for 500 hours at 60 ℃ under the environment of 90% relative humidity is within + -0.15%,

< shear test >)

recovery (%) = (strain amount a-strain amount B)/strain amount a×100.

2. The optical adhesive tape according to claim 1, wherein the optical adhesive tape satisfies the following formula:

|C×D|≤3

in the above-mentioned method, the step of,

c is the average dimensional change rate [% ] in the width direction and in the longitudinal direction when the optical adhesive tape is heated at 60 ℃ in an environment with a relative humidity of 90% for 500 hours,

d is the maximum curl amount [ mm ] of the laminate obtained by bonding the adhesive layer of the optical adhesive tape to a PET film having a thickness of 50 μm and cutting it to 10cm square and heating the laminate at 60℃under an environment having a relative humidity of 90% for 500 hours,

maximum curl: placing the laminate on a horizontal plane with the curled convex surface of the laminate being the lower side, and setting the highest warpage amount of the 4-angle warpage amounts as the maximum curling amount D [ mm ]; the maximum curl amount measured with the laminate placed on a horizontal plane with the PET film side of the laminate being the lower side is set to +, and the maximum curl amount measured with the laminate placed on a horizontal plane with the base material side of the laminate being the lower side is set to +.

3. The optical adhesive tape according to claim 1 or 2, wherein the strain amount a of the adhesive layer is 3% or more.

4. The optical adhesive tape according to any one of claims 1 to 3, wherein the strain amount B of the adhesive layer is 0.1% or more.

5. The optical adhesive tape according to any one of claims 1 to 4, wherein the substrate has a glass transition temperature (Tg) of 60 ℃ or higher.

6. The optical adhesive tape according to any one of claims 1 to 5, wherein the adhesive layer has a glass transition temperature (Tg) of-10 ℃ or less.

7. The optical adhesive tape according to any one of claims 1 to 6, wherein the optical adhesive tape has a humidity expansion ratio of 0.1% or less when the optical adhesive tape is humidified from 60 ℃ to 30% relative humidity to 60 ℃ and 60% relative humidity.

8. The optical adhesive tape according to any one of claims 1 to 7, wherein the substrate has a coefficient of humidity expansion of 5 x 10 ^-5 The following/%RH.

9. The optical adhesive tape according to any one of claims 1 to 8, wherein the second surface of the substrate is subjected to an antireflection treatment and/or an antiglare treatment.

10. The optical adhesive tape according to any one of claims 1 to 9, wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer.

11. An image display device obtained by laminating an image display panel and the optical adhesive tape according to any one of claims 1 to 10.

12. A tiled display, wherein the tiled display is obtained by arranging a plurality of the image display devices according to claim 11.